Coated sensors and methods related thereto

ABSTRACT

The invention provides coated sensors for detecting the presence of analytes. The sensor comprises one or more fluorescent sources, such as one or more quantum dots or one or more fluorescent dyes, a polymeric matrix, a surface coating, and one or more analyte sensing components. The surface coating may be a conformal polymeric film, permeable to the analyte, which may be deposited via a solventless process such as initiated chemical vapor deposition or photoinitiated chemical vapor deposition. The surface coating may increase the biocompatibility of the sensor, reduce nonspecific protein adsorption, and/or sequester functional sensor components within the sensor. The invention also provides methods for detecting the presence of an analyte with coated sensors of the invention.

CROSS-REFERENCE TO RELATED CASES

This application claims the benefit of U.S. Provisional PatentApplication No. 61/191,467, entitled “Coated Sensors and Methods RelatedThereto” filed on Sep. 8, 2008, the entire disclosure of which is herebyincorporated by reference as if set forth herein in its entirety.

BACKGROUND OF THE INVENTION

Biological sensors are very useful for monitoring and understandingbiological mechanisms, both within individual cells and in more generalbiological environments such as the human body: For example,intra-cellular sensors offer a powerful tool for understanding themechanisms within a cell. Such sensors can detect the presence orconcentration of an analyte within the cell, and when multiple sensorsare distributed within the interior of the cell, the presence ofanalytes in relation to different cellular organelles and the cellmembrane can be better understood.

An important consideration for sensors deployed for biologicalapplications is compatibility with the physiological environment.Sensors in the physiological environment are extremely susceptible tononspecific adsorption of biological materials such as proteins. Thisnonspecific adsorption may degrade sensor performance as well as causeinflammation and thrombosis. Therefore, methods or compositions thatreduce nonspecific adsorption to biological sensors would be highlydesirable.

SUMMARY OF THE INVENTION

The invention discloses coated sensors, e.g., for detecting the presenceof analytes in biological media. The coating may be a polymer coating,such as a biocompatible polymer coating, e.g., that is permeable to thesensor's analyte. The coating may be substantially continuous andconformal across planar and/or nonplanar surfaces of the sensor(particularly those surfaces intended to contact the analyte solution),with thicknesses preferably ranging from approximately 50 nm to 2 μm.The coating may be formed in situ with a solventless surfacepolymerization process; using such methods can reduce or eliminate thepresence of solvent molecules within the coating, thus attenuating oreliminating biocompatibility issues that may arise from leaching ofsolvent trapped in the coating into a biological environment, as well asthe effects of solvent tension on coating formation, which can result inagglomeration of individual sensors and/or patchiness in the coating.

In certain embodiments, sensors and sensor particles are coated with apolymer coating deposited via initiated chemical vapor deposition (iCVD)or photoinitiated chemical vapor deposition (piCVD). In certainembodiments, the sensor coating may be biocompatible.

In certain embodiments, the subject sensors are ion-selective optodesthat produce an observable optical signal indicative of theconcentration of a target analyte. In certain such embodiments, thesubject sensors are coated ion-selective sensors comprising quantum dotsand/or fluorescent dyes and capable of selectively measuring ions, e.g.,Na⁺, K⁺, Cl⁻, etc., in the cytosol of a single living cell. Quantum dotsare attractive probes for microscopy due to their photophysicaladvantages over fluorescent dyes, including prolonged photostability,brightness and quantum efficiency. In certain embodiments, a sensorcomprises one or more quantum dots and/or fluorescent dye or dyes, apH-sensitive dye, and optionally an ion-selective component such as anionophore. These elements may, for example, be disposed in a polymermatrix and/or in the surface coating. In certain embodiments, thesensors may detect ionic analytes by selective ion extraction by thepolymer matrix and/or coating, thereby inducing a pH change within thesensor which in turn changes the absorbance of the pH-sensitive dye. Thechange of absorbance may in turn attenuate the intensity of detectableemissions, e.g., fluorescence, from the one or more quantum dots and/orfluorescent dye or dyes by directly absorbing their fluorescenceemissions.

In other embodiments, the subject sensors include coated sensors andsensor particles that may detect the presence of a chelatable analyte,such as glucose, comprising a quantum dot and/or a fluorescent dye ordyes, a polymer matrix comprising a polymer including moieties that bindthe chelatable analyte, a chromophore associated with the polymer matrixthat binds to the moieties in the absence of the chelatable analyte, anda surface coating. In some embodiments, photons emitted by the quantumdot in an excited state are absorbed by the chromophore in an unboundstate but not by the chromophore in a bound state. The moieties may bindthe chelatable analyte and chromophore reversibly and competitively. Incertain embodiments, the moieties are boronic acids or boronic esters.In some embodiments, one or more components of the sensor, such as themoieties and/or chromophore, are covalently bound to or associated withthe polymer matrix.

In certain aspects, the invention comprises methods for detecting thepresence of an analyte in a medium using the sensors and sensorparticles of the invention. In certain such embodiments, the analyte isan ion, while in other embodiments, the analyte is a chelatable analyte,such as glucose. In certain embodiments, the medium is selected fromair, water, blood, plasma, urine, and cytoplasm. In certain embodiments,the invention comprises a method for detecting the presence of ananalyte in a plant or animal. In certain such embodiments, the sensorparticle is placed in contact with cells in biological samples such astissues outside of the host specimen. In certain such embodiments, thesensors are introduced to cells within a host specimen. In certain suchembodiments, the sensor particle is implanted in the dermis or epidermisof an animal and an analyte, such as glucose, is monitored.

In certain embodiments, the polymer matrix and/or surface coating maycomprise an internalizing moiety which assists the sensor in localizingwithin the cytosol of a cell. In certain embodiments, the internalizingmoiety comprises a small molecule or peptide, such as an amine, thatreacts, e.g., under acidic conditions, to release a sensor from theconfines of an endosome.

BRIEF DESCRIPTION OF DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawings will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1. A schematic diagram of a cell assay system according to anillustrative embodiment of the invention.

FIG. 2. Sensor particle 3, coated with a coating 28, with (a)chromophore 2 bound to moiety 1, wherein the bound chromophore emitsphotons 4 at one wavelength and (b) moiety 1 bound to analyte 5 whereinthe unbound chromophore 2 emits photons at a second wavelength 6.

FIG. 3. Sensor particle 3, coated with a coating 28 with (a) chromophore2 bound to moiety 1, wherein the bound chromophore 2 does not absorbphotons 4 emitted by the quantum dot and/or fluorescent dye 7 and (b)moiety 1 bound to analyte 5 wherein unbound chromophore 2 absorbsphotons 4 emitted by quantum dot and/or fluorescent dye 7.

FIG. 4. Sensor particle 3, coated with a coating 28 with a. chromophore2 bound to moiety 1, wherein the bound chromophore absorbs photons 4emitted by the quantum dot and/or fluorescent dye 7 and b. moiety 1bound to analyte 5 wherein unbound choromophore 2 absorbs photons 4emitted by quantum dot and/or fluorescent dye 7.

FIG. 5. Cross sections (a-d) of various optical sensor arrangementssuitable for use in various implementations of a cell assay system.

FIG. 6. An embodiment (a-b) of a microfluidic device in accord with thepresent invention.

FIG. 7. Selectivity of the nanosensor of the invention for iondetection.

FIG. 8. Experimental response to sodium. (a) Spectral response ofimmobilized sensors to increasing concentrations of sodium. (b)Calibration curve of ratiometric sensors.

FIG. 9. Spectral overlap of a quantum dot that fluoresces at 655 nm andthe absorbance of a chromoionophore at varying sodium concentrations.

FIG. 10. Biocompatibility of nanosensors in HEK cells. HEK cells wereincubated with either control (water), nanosensors without quantum dots(nans), quantum dot nanosensors (ISQD), 100 nm gold nanoparticles, or 20nm latex beads (a negative control) and viability (y-axis) wasevaluated.

FIG. 11. Confocal image of nanosensors without quantum dots loaded intoan HEK 293 cell.

FIG. 12. A LIVE/DEAD assay wherein nanosensors with quantum dots wereloaded into HEK 293 cells overnight and then stained. The greenindicates healthy cells, while the red stains the nuclei of dead cells.No difference in the ratio of live to dead cells was noted betweennanosensor loaded cells and control (no nanosensors).

FIG. 13. (a) fluorescence image of an isolated neonatal rat ventricularmyocyte loaded with sodium-selective nanosensors. (b) the fluorescencecollected from a nanosensor in a cardiac cell during stimulation.

FIG. 14. A representation of two exemplary modes of operation of thequantum dot incorporated coated sensor for the detection of cationicanalytes. In mode A, the sensor fluoresces in the presence of the ionicanalyte. In mode B, the sensor fluoresces in the absence of ionicanalyte.

FIG. 15. A representation of two exemplary modes of operation of thequantum dot incorporated coated sensor for the detection of anionicanalytes. In mode A, the sensor fluoresces in the presence of the ionicanalyte. In mode B, the sensor fluoresces in the absence of ionicanalyte.

FIG. 16. A representation of a sensor coated with a surface modifiersuch as PEG.

FIG. 17. Spectral signature of the components of a glucose sensitivesensor; (a) overlap of normalized alizarin absorbance and quantum dotemission, (b) individual contribution of the two components of the innerfilter effect at high and low glucose concentration and the resultingoverall fluorescence signal.

FIG. 18. Wide field fluorescence microscopic image of a suspension ofsensor particles.

FIG. 19. Nanometer-sized sensor particles demonstrating the inner filtereffect wherein: (a) the absorbance changes from purple to yellowdepending on the binding state of the chromophore; (b) the same samplesunder UV excitation wherein the sample that was visually purple does notabsorb the 525 nm emission of the quantum dots and fluoresces brightly,while the yellow sample absorbs the fluorescence emission of the quantumdot and has minimal emission.

FIG. 20. Evaluating response to glucose, the sensor particles containingthe essential sensing components, alizarin, pyrene boronic acid andadditive, was immobilized to the bottom of a micro-well for calibration.Response to glucose and fructose was measured, the average ±SEM isshown, where n=6 and n=8 for control and monosaccharides, respectively.

FIG. 21. An exemplary embodiment of a piCVD reactor used for coatingsamples.

FIG. 22. FTIR spectra of (a) standard pHEMA and (b) piCVD pHEMA.

FIG. 23. Typical reversible swelling response of piCVD pHEMA in buffersolution for multiple swell/dry cycles.

FIG. 24. Equilibrium swollen water content as a function of (a) vaporresidence time and (b) fractional saturation of monomer duringdeposition.

FIG. 25. Average mesh size of swollen films.

FIG. 26. Surface nitrogen content of bare silicon and pHEMA afterincubation in a 1 wt % protein solution for three hours at 37° C.

FIG. 27. Response curves of (a) uncoated optode and (b) optode coatedwith 100 nm piCVD pHEMA when submerged in pH 7.4 buffer containing I-0Na+ions, II-140 mM Na+ions, III-340 mM Na+ions, and IV-140 mM Na+ions.

FIG. 28. SEM cross-section of a silica microsphere coated with piCVDpHEMA at (a) 1600× magnification (scale bar=10 μm) and (b) 5500×magnification (scale bar=2 μm). The arrows indicate the polymer layer.

FIG. 29. SEM images of (a) uncoated silica microspheres and (b) silicamicrospheres coated with piCVD pHEMA. Both images were obtained at 1600×magnification and the scale bars represent 10 μm.

DETAILED DESCRIPTION OF THE INVENTION

In brief overview, embodiments of the present invention provide coatedsensors and related systems, methods, and devices for measuring ionicand/or chelatable analytes. Suitable coatings are preferably permeableto the analyte of interest. In certain embodiments, the coating acts asa barrier. Such coatings serve to protect and/or contain the functionalcomponents within the sensor, and thus may be substantially impermeableto one or more of: 1) functional components of the sensor (such as dyes,chromionophores, and other components disclosed herein), therebyinhibiting leaching of the functional components from the sensor andthereby extending the useful lifetime of the sensor; and 2) componentsof the analyte solution that could degrade the sensor or any of itscomponents. In certain embodiments, the coating acts as a biocompatiblecoating. In certain embodiments, the coating acts both as a barrier andas a biocompatible coating.

In certain embodiments, initiated chemical vapor deposition (iCVD), acoating technology, may be used to deposit a layer that protects thesensors from the surrounding medium. The solventless nature of iCVDparticle coating may offer an advantage over solution-based methods thatrely on drying of a wet polymer solution. In certain embodiments, theiCVD particle coating employs a rotating bed reactor which providesconformal coating of microspheres and nanoparticles without inducingaggregation. In certain embodiments, the polymer or copolymer comprisesone or more recurring monomeric units selected from

wherein, independently for each occurrence:

-   R is selected from hydrogen and alkyl;-   R¹ is selected from hydrogen, alkyl, aralkyl, heteroaralkyl, and    carboxyl;-   R² is selected from hydrogen, methyl, bromine, and chlorine;-   X is selected from hydrogen, alkyl, cycloalkyl, heterocycloalkyl,    aryl, heteroaryl, aralkyl, heteroaralkyl, and —(CH₂)_(n)Y, wherein X    is optionally substituted, e.g., by one or more of halo, alkyl,    hydroxyl, and alkoxy; and-   Y is selected from hydrogen, alkyl, haloalkyl such as monohaloalkyl,    dihaloalkyl and perhaloalkyl, cycloalkyl, heterocycloalkyl, aryl,    heteroaryl, aralkyl, heteroaralkyl, nitro, halo, hydroxyl, alkoxy,    aryloxy, carboxyl, heteroaryloxy, amino, acylamino, amido,    carbamoyl, sulfhydryl, sulfonate and sulfoxido; and n is 1-10    inclusive. The term “copolymer” as used herein means a polymer of    two or more different monomers, including alternating, block, and    random copolymers.

Unless otherwise specified, any of alkyl, cycloalkyl, heterocycloalkyl,aryl, heteroaryl, aralkyl, heteroaralkyl and any other group in whichhydrogen atoms are covalently appended to carbon atoms, may optionallybe substituted, i.e., substitution of hydrogen atoms, by one or moresubstituents such as halogen, alkyl, hydroxyl and alkoxy.

In certain embodiments, the polymer or copolymer comprises one or morerecurring monomeric units selected from poly(glycidyl methacrylate),p-bromophenyl methacrylate, pentabromophenyl methacrylate, n-vinylcarbazole, p-divinyl benzene, styrene, alpha methyl styrene,2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 2,3-dichlorostyrene,2,4-dichlorostyrene, 2,5-dichlorstyrene, 2,6-dichlorostyrene,3,4-dichlorostyrene, 3,5-dichlorostyrene, 2-bromostyrene,3-bromostyrene, 4-bromostyrene, 2,3-dibromostyrene, 2,4-dibromostyrene,2,5-dibromostyrene, 2,6-dibromostyrene, 3,4-dibromostyrene,3,5-dibromostyrene, methyl acrylate, n-butyl acrylate, n-pentylacrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate,2-ethylhexyl acrylate, perfluorocyclohexylmethyl acrylate,perfluorodecylacrylate, pentafluorophenyl methacrylate, benzyl acrylate,2-hydroxyethyl acrylate, dimethylaminoethyl acrylate, Et₃DMAA(N,N-dimethylacetoacetamide), sec-butyl acrylate, tert-butyl acrylate,isobornyl acrylate, ethylene glycol, ethylene glycol diacrylate, methylmethacrylate, ethyl methacrylate, n-propyl methacrylate, n-butylmethacrylate, isobutyl methacrylate, n-pentyl methacrylate, t-butylmethacrylate, dimethylaminoethyl methacrylate, hydroxyethylmethacrylate, cyclohexyl methacrylate, benzyl methacrylate, isobornylmethacrylate, glycidyl methacrylate, ethylene glycol dimethacrylate,methacrylic acid, styrene, alpha-methyl styrene, 2,4-dimethyl styrene,2,5-dimethyl styrene, m-divinylbenzene, p-divinylbenzene,vinylimidazole, N-vinyl-2-pyrrolidinone, V3D3 (3901-77-7),1,4-divinyloxybutane (3891-33-6), diethylene glycol divinyl ether(764-99-8), 1,5-hexadiene-3,4-diol DVG (1069-23-4), methyltranscinnamate, N-morpholinoethyl acrylate, 2-morpholinoethylmethacrylate, 2-isocyanatoethylmethacrylate, 2-sulfoethyl emthacrylate,2-methoxyethyl methacrylate, 2-(tert-butylamino)ethyl methacrylate,2-ethoxyethyl methacrylate, 2-chloroethyl methacrylate, 2-hydroxypropylmethacrylate, 2-diethylaminoethyl methacrylate, cyclopentylmethacrylate, 2-(diisopropylamino)ethyl methacrylate, 2-bromoethylmethacrylate and 2-phenylethyl methacrylate.

In certain embodiments, the polymer or copolymer comprises one or morerecurring monomeric units selected from hydroxyethylmethacrylate (HEMA),perfluorodecylacrylate, ethylene glycol, and pentafluorophenylmethacrylate. In certain embodiments, the polymer or copolymer comprisesone or more methacrylate monomers, e.g., HEMA and pentafluorophenylmethacrylate. In certain embodiments, the copolymer comprises HEMA andperfluorodecylacrylate, e.g. poly(HEMA-co-perfluorodecylacrylate). Incertain embodiments, the copolymer comprises ethylene glycol, HEMA, andmethacrylate, e.g., poly(HEMA-co-poly(ethylene glycol)ethyl ethermethacrylate). In certain embodiments, the copolymer comprises HEMA andpentafluoromethacrylate, e.g., poly(HEMA-co-pentafluorophenylmethacrylate).

In certain embodiments, the polymer or copolymer comprises one or morerecurring monomeric units selected from the formulas above where X is—(CR′R′)_(n)Y and R′ at each occurrence is selected from hydrogen orfluoro. In particular embodiments, Y is selected from haloalkyl such asperhaloalkyl such as perfluoromethyl. In particular embodiments, n isselected from 1-10, such as 9, and R′ at each occurrence is fluoro. Incertain embodiments, X is perfluorodecyl.

The term “acyl” is art-recognized and refers to a group represented bythe general formula hydrocarbylC(O)—, preferably alkylC(O)—.

The term “acylamino” is art-recognized and refers to an amino groupsubstituted with an acyl group and may be represented, for example, bythe formula hydrocarbylC(O)NH—.

The term “alkyl” refers to saturated aliphatic substituents, includingstraight-chain alkyl groups and branched-chain alkyl groups. Inpreferred embodiments, a straight-chain or branched chain alkyl has 30or fewer carbon atoms in its backbone (e.g., C1-C30 for straight chains,C3-C30 for branched chains), and more preferably 20 or fewer. Examplesof straight-chain and branched alkyl groups include methyl, ethyl,n-propyl, iso-propyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl,pentyl and octyl.

Moreover, the term “alkyl” (or “lower alkyl”) as used throughout thespecification, examples, and claims is intended to include both“unsubstituted alkyls” and “substituted alkyls”, the latter of whichrefers to alkyl moieties having substituents replacing a hydrogen on oneor more carbons of the hydrocarbon backbone. Such substituents caninclude, for example, a halogen, a hydroxyl, a carbonyl (such as acarboxyl, an alkoxycarbonyl, a formyl, or an acyl), a thiocarbonyl (suchas a thioester, a thioacetate, or a thioformate), an alkoxyl, aphosphoryl, a phosphate, a phosphonate, a phosphinate, an amino, anamido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl,an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, asulfonyl, a heterocyclyl, an aralkyl, or an aryl or heteroaryl moiety.It will be understood by those skilled in the art that the moietiessubstituted on the hydrocarbon chain can themselves be substituted, ifappropriate. For instance, the substituents of a substituted alkyl mayinclude substituted and unsubstituted forms of amino, azido, imino,amido, phosphoryl (including phosphonate and phosphinate), sulfonyl(including sulfate, sulfonamido, sulfamoyl and sulfonate), and silylgroups, as well as ethers, alkylthios, carbonyls (including ketones,aldehydes, carboxylates, and esters), —CF₃, —CN and the like. Exemplarysubstituted alkyls are described below. Cycloalkyls can be furthersubstituted with alkyls, alkenyls, alkoxys, alkylthios, aminoalkyls,carbonyl-substituted alkyls, —CF₃, —CN, and the like.

The term “Cx-y” when used in conjunction with a chemical moiety, suchas, acyl, acyloxy, alkyl, alkenyl, alkynyl, or alkoxy is meant toinclude groups that contain from x to y carbons in the chain. Forexample, the term “C_(x-y)alkyl” refers to substituted or unsubstitutedsaturated hydrocarbon groups, including straight-chain alkyl andbranched-chain alkyl groups that contain from x to y carbons in thechain, including haloalkyl groups such as trifluoromethyl and2,2,2-trifluoroethyl, etc. C₀ alkyl indicates a hydrogen where the groupis in a terminal position, a bond if internal. The terms“C_(2-y)alkenyl” and “C_(2-y)alkynyl” refer to substituted orunsubstituted unsaturated aliphatic groups analogous in length andpossible substitution to the alkyls described above, but that contain atleast one double or triple bond respectively.

The term “alkoxy” refers to an alkyl group having an oxygen attachedthereto. Representative alkoxy groups include methoxy, ethoxy, propoxy,tert-butoxy and the like.

The term “amide”, as used herein, refers to a group

wherein R₉ and R₁₀ each independently represent a hydrogen orhydrocarbyl group, or R₉ and R₁₀ taken together with the N atom to whichthey are attached complete a heterocycle having from 4 to 8 atoms in thering structure.

The terms “amine” and “amino” are art-recognized and refer to bothunsubstituted and substituted amines and salts thereof, e.g., a moietythat can be represented by

wherein R₉, R₁₀, and R₁₀′ each independently represent a hydrogen or ahydrocarbyl group, or R₉ and R₁₀ taken together with the N atom to whichthey are attached complete a heterocycle having from 4 to 8 atoms in thering structure.

The term “aralkyl”, as used herein, refers to an alkyl group substitutedwith an aryl group. Examples of aralkyl include benzyl, pyridinylmethyl,thiophenylbutyl, and phenethyl.

The term “aryl” as used herein include substituted or unsubstitutedsingle-ring aromatic groups in which each atom of the ring is carbon.Preferably the ring is a 5- to 7-membered ring, more preferably a6-membered ring. The term “aryl” also includes polycyclic ring systemshaving two or more cyclic rings in which two or more carbons are commonto two adjoining rings wherein at least one of the rings is aromatic,e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls,cycloalkynyls, aryls, heteroaryls, and/or heterocyclyls. Aryl groupsinclude benzene, naphthalene, phenanthrene, phenol, aniline, and thelike.

The term “carbamate” or “carbamoyl” is art-recognized and refers to agroup

wherein R⁹ and R¹⁰ independently represent hydrogen or a hydrocarbylgroup.

The terms “carbocycle”, “carbocyclyl”, and “carbocyclic”, as usedherein, refers to a non-aromatic saturated or unsaturated ring in whicheach atom of the ring is carbon. Preferably a carbocycle ring containsfrom 3 to 10 atoms, more preferably from 5 to 7 atoms. Each ring of apolycicylic carbocycle may be selected from saturated, unsaturated andaromatic rings. In an exemplary embodiment, an aromatic ring, e.g.,phenyl, may be fused to a saturated or unsaturated ring, e.g.,cyclohexane, cyclopentane, or cyclohexene. Any combination of saturated,unsaturated and aromatic bicyclic rings, as valence permits, areincluded in the definition of carbocyclic. Exemplary carbocycles includecyclopentyl, cyclohexyl, cyclohexenyl, adamantyl, phenyl and naphthyl.

A cycloalkyl group is a carbocycle which is completely saturated. Unlessotherwise specified, cycloalkyl refers to 3-8 membered monocylic and7-12 membered bicyclic rings. Exemplary cycloalkyl groups includecyclopentyl, cyclohexyl, bicyclo[2,2,1]heptanyl and adamantyl.

The terms “hetaralkyl” and “heteroaralkyl”, as used herein, refers to analkyl group substituted with a heteroaryl group.

The terms “heteroaryl” and “hetaryl” include substituted orunsubstituted aromatic single ring structures, preferably 5- to7-membered rings, more preferably 5- to 6-membered rings, whose ringstructures include at least one heteroatom, preferably one to fourheteroatoms, more preferably one or two heteroatoms. The terms“heteroaryl” and “hetaryl” also include polycyclic ring systems havingtwo or more cyclic rings in which two or more carbons are common to twoadjoining rings wherein at least one of the rings is heteroaromatic,e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls,cycloalkynyls, aryls, heteroaryls, and/or heterocyclyls. Heteroarylgroups include, for example, pyrrole, furan, thiophene, imidazole,oxazole, thiazole, pyrazole, pyridine, pyrazine, pyridazine, andpyrimidine, and the like.

The term “heteroatom” as used herein means an atom of any element otherthan carbon or hydrogen. Preferred heteroatoms are nitrogen, oxygen, andsulfur.

The term “heterocycloalkyl”, “heterocycle”, and “heterocyclic” refer tosubstituted or unsubstituted non-aromatic ring structures, preferably 3-to 10-membered rings, more preferably 3- to 7-membered rings, whose ringstructures include at least one heteroatom, preferably one to fourheteroatoms, more preferably one or two heteroatoms. The terms“heterocyclyl” and “heterocyclic” also include polycyclic ring systemshaving two or more cyclic rings in which two or more carbons are commonto two adjoining rings wherein at least one of the rings isheterocyclic, e.g., the other cyclic rings can be cycloalkyls,cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and/orheterocycloalkyls. Heterocyclyl groups include, for example, piperidine,piperazine, pyrrolidine, morpholine, lactones, lactams, and the like.

The term “hydrocarbyl”, as used herein, refers to a group that is bondedthrough a carbon atom that does not have a ═O or ═S substituent, andtypically has at least one carbon-hydrogen bond and a primarily carbonbackbone, but may optionally include heteroatoms. Thus, groups likemethyl, ethoxyethyl, 2-pyridyl, and trifluoromethyl are considered to behydrocarbyl for the purposes of this application, but substituents suchas acetyl (which has a ═O substituent on the linking carbon) and ethoxy(which is linked through oxygen, not carbon) are not. Hydrocarbyl groupsinclude, but are not limited to aryl, heteroaryl, carbocycle,heterocycle, alkyl, alkenyl, alkynyl, and combinations thereof.

The term “lower” when used in conjunction with a chemical moiety, suchas, acyl, acyloxy, alkyl, alkenyl, alkynyl, or alkoxy is meant toinclude groups where there are ten or fewer non-hydrogen atoms in thesubstituent, preferably six or fewer. A “lower alkyl”, for example,refers to an alkyl group that contains ten or fewer carbon atoms,preferably six or fewer. In certain embodiments, acyl, acyloxy, alkyl,alkenyl, alkynyl, or alkoxy substituents defined herein are respectivelylower acyl, lower acyloxy, lower alkyl, lower alkenyl, lower alkynyl, orlower alkoxy, whether they appear alone or in combination with othersubstituents, such as in the recitations hydroxyalkyl and aralkyl (inwhich case, for example, the atoms within the aryl group are not countedwhen counting the carbon atoms in the alkyl substituent).

The term “substituted” refers to moieties having substituents replacinga hydrogen on one or more carbons of the backbone. It will be understoodthat “substitution” or “substituted with” includes the implicit provisothat such substitution is in accordance with permitted valence of thesubstituted atom and the substituent, and that the substitution resultsin a stable compound, e.g., which does not spontaneously undergotransformation such as by rearrangement, cyclization, elimination, etc.As used herein, the term “substituted” is contemplated to include allpermissible substituents of organic compounds. In a broad aspect, thepermissible substituents include acyclic and cyclic, branched andunbranched, carbocyclic and heterocyclic, aromatic and non-aromaticsubstituents of organic compounds. The permissible substituents can beone or more and the same or different for appropriate organic compounds.For purposes of this invention, the heteroatoms such as nitrogen mayhave hydrogen substituents and/or any permissible substituents oforganic compounds described herein which satisfy the valences of theheteroatoms. Substituents can include any substituents described herein,for example, a halogen, a hydroxyl, a carbonyl (such as a carboxyl, analkoxycarbonyl, a formyl, or an acyl), a thiocarbonyl (such as athioester, a thioacetate, or a thioformate), an alkoxyl, a phosphoryl, aphosphate, a phosphonate, a phosphinate, an amino, an amido, an amidine,an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, asulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, aheterocyclyl, an aralkyl, or an aromatic or heteroaromatic moiety. Itwill be understood by those skilled in the art that the moietiessubstituted on the hydrocarbon chain can themselves be substituted, ifappropriate.

Fluoro-substituted includes from one fluoro substituent up toper-fluoro-substitution. Exemplary fluoro-substituted C₁-C₂ alkylincludes —CFH₂, CF₂H, —CF₃, —CH₂CH₂F, —CH₂CHF₂, —CHFCH₃, —CF₂CHF₂.Per-fluoro-substituted C₁-C₂ alkyl, for example, includes —CF₃, and—CF₂CF₃.

The term “sulfoxide” is art-recognized and refers to the group —S(O)—R₉,wherein R₉ represents a hydrocarbyl.

The term “sulfonate” is art-recognized and refers to the group—OS(O)₂—R₉, wherein R₉ represents a hydrocarbyl.

In certain embodiments, photoinitiated chemical vapor deposition(piCVD), a coating technology, may be used to deposit a layer thatprotects the sensors from the surrounding medium. In addition to thebenefits of iCVD disclosed above, piCVD has the additional advantage ofnot requiring a separate polymerization initiator. In certainembodiments, the piCVD particle coating employs a reactor which providesconformal coating of microspheres and nanoparticles, e.g., withoutinducing aggregation. In certain embodiments, the primary monomer forthe piCVD coatings of sensors is hydroxyethylmethacrylate (HEMA)monomer. In certain embodiments, the piCVD coatings of sensors comprisesubstantially pure poly(HEMA), while in other embodiments the coatingscomprise copolymers comprising HEMA and one or more of the monomers andpolymers, e.g., selected from those disclosed above. In certainembodiments, the HEMA polymer or copolymer is crosslinked as a result ofphotodegradation of the hydroxyethyl ester.

CVD generally takes place in a reactor wherein the surface to be coatedis placed on a stage in the reactor and gaseous precursor molecules arefed into the reactor. The stage may simply be the bottom of the reactorand not a separate entity. CVD provides a uniform or substantiallyuniform coating on rough, fibrous, and porous morphologies with highsurface areas. The CVD coating process is compatible with a variety oforganic and inorganic materials. Any embodiments disclosed forapplication with CVD may also be used with particular CVD methods suchas iCVD or piCVD.

The CVD coating process can take place at a range of pressures fromatmospheric pressure to low vacuum. In certain embodiments, the pressureis less than about 500 mtorr, such as less than about 400 mtorr, such asless than about 300 mtorr, such as less than about 200 mtorr, such asabout 100 mtorr.

The CVD coating process can take place at a range of temperatures. Incertain embodiments, the temperature is ambient temperature. In certainembodiments the temperature is about 20° C., about 25° C., about 30° C.,about 35° C. or about 40° C. In certain embodiments the temperature isbetween about 0° C. and about 100° C., or between about 20° C. and about50° C. In certain embodiments, the stage temperature may be variedduring the coating process.

The CVD coating process can take place using a range of monomerflowrates. In certain embodiments, the properties of the resultantpolymer and the speed of the deposition can be controlled by the partialpressure of a monomer, e.g., HEMA, divided by the saturation pressure ofthe monomer evaluated at the stage temperature, i.e. P_(M)/P_(M) ^(sat).In certain embodiments, P_(M)/P_(M) ^(sat) is between about 0.10 andabout 1.0, such as about 0.2, such as about 0.3, such as about 0.4, suchas about 0.5, such as about, 0.6, such as about 0.7, such as about 0.8,such as about 0.9 or in particular about 0.4.

In certain embodiments, flowrate of a monomer in the coating process mayrange from about 0.1 to about 3.0 standard cubic centimeters per minute(sccm) such as about 1.0, such as about 1.5, such as about 2.0, such asabout 2.5 sccm. In certain embodiments, the flowrate may be variedduring the coating process.

In certain embodiment, the coating process takes place at a temperaturebetween about 20° C. and about 50° C., a pressure of about 100 mtorr, aflowrate as measured by P_(M)/P_(M) ^(sat) between about 0.10 and about1.0 such as about 0.4 and ranging from about 0.5 to about 3.0 sccm suchas about 2 sccm.

In certain embodiments, the coatings of the sensors or sensor particlesare essentially pure polymer and little or no residual solvent ispresent, e.g., that may cause implant rejection, irritation, or otherunwanted side effects. In certain embodiments, there may be less than1.0%, 0.5%, 0.1%, or even less than 0.05% or 0.01% of residual solventin the coating. The coatings may be applied at room temperature in asingle step, taking only a few minutes of total time. In certainembodiments, the composition may be controlled by changing the gas feedmix and thickness may be controlled by in situ monitoring. In certainembodiments, coating film crosslinking, which affects film swellingcharacteristics, mesh size, and analyte permeability, may be controlledby the choice of temperature during the coating process. In certainembodiments, the coatings of the sensors are substantially conformal. Incertain embodiments, the coatings of the sensors display less than 20%,15%, 10%, 5%, or even less than 2% or 1% of thickness variation over thecoated surface.

Graft density is a measure of the number of covalent bonds a polymermakes to substrate per unit contact area, and often correlates to howstrongly a polymer is adhered to a substrate. In certain embodiments,the coatings of the sensors have graft densities greater than 1 chainper square millimeter, or even greater than 1 chain per square micron,e.g., ranging from 0.001 to 10 chains per square nanometer, or from 0.01to 1 chains per square nanometer.

Free radical polymerization initiators may be used to initiatepolymerization in the iCVD coating process. Free radical polymerizationinitiators may include halogens such as chlorine, azo compounds such asazobisisobutyronitrile (AIBN) or1,1′-(Z)-diazene-1,2-diyldicyclohexanecarbonitrile (ABCN), or organicperoxides such as tert-butyl peroxide or benzoyl peroxide. The use offree radical polymerization initiators in a polymerization reaction mayresult in the formation of initiator fragments. Examples of initiatorfragments may include cyanoisobutyl (from AIBN), cyanocyclohexyl (fromABCN), tert-butoxyl (from tert-butyl peroxide), or benzoyloxy (frombenzoyl peroxide). In certain embodiments, coatings of sensors or sensorparticles may be substantially free of initiator fragments, or maycomprise less than 1.0%, 0.5%, 0.1%, or even less than 0.05% or 0.01% ofinitiator fragments.

In certain embodiments, the coatings are durable under usage condition,e.g., remain substantially intact after prolonged immersion in aqueousbuffer solution and repeated cycling between wet and dry conditions. Incertain embodiments, the coatings exhibit reversible swelling propertiesunder repeated cycling between wet and dry states, e.g., remainsubstantially continuous and/or displays substantially no thickness lossbetween cycles, e.g., less than 40%, 30%, 20%, or even less than 10% or1.0% thickness loss between cycles.

Varying the thickness of the coating can effect functional parameters ofthe sensor. Increasing the thickness will increase the transit time ofan analyte through the coating into the sensor, thereby increasing theresponse time of the sensor. However, increasing the thickness of thecoating can also enhance its protective value, potentially increasingthe useful life of the sensor. Typical coating thicknesses range from 1nm to 100 microns, e.g., 10 nm to 10 microns.

Sensor coatings may be further modified, e.g., subsequent to deposition.In certain embodiments, the sensor further comprises a surface modifier(SM). In certain embodiments, the SM comprises a molecule that promotesthe delivery or localization of the sensor within a cell. SMs of theinvention include molecules with a hydrophilic portion 40 and ahydrophobic portion 42, FIG. 15. In certain embodiments, the hydrophobicportion 42 of the SM anchors the SM to the hydrophobic polymer matrix41. In certain embodiments, the SM is disposed on the surface of thesensor, e.g., covers a portion of the surface or covers the entiresurface. In certain embodiments, the SM is disposed on the surface ofthe coated sensor, e.g., on all or a portion of the coated surface. Incertain embodiments, the sensor coating may comprise the SM. Exemplaryhydrophobic portions 42 of the SM include but are not limited to, lipidsand hydrophobic polymers. In certain embodiments, the hydrophilicportion 40 of the SM is disposed on the surface of the sensor. Anexemplary hydrophilic portion 40 includes, but is not limited to,polyethylene glycol (PEG). In certain embodiments, the hydrophilicportion (PEG) is bound to the hydrophobic portion (lipid) through alinker (e.g., phosphate, ceramide).

In certain embodiments, the sensor further comprises a targeting moiety.In certain embodiments, the targeting moiety is bound to the polymermatrix. In certain embodiments, the targeting moiety is bound to the SMon the surface of the polymer matrix. In certain embodiments, thetargeting moiety is coupled to the sensor coating. In certainembodiments, the targeting moiety may be coupled to the SM, which inturn may be coupled to the surface of the polymer matrix or to thesensor coating. In certain embodiments, the sensor coating comprises thetargeting moiety. The targeting moiety, which assists the sensor inlocalizing to a particular target area, entering a target cell(s),and/or locating proximal to an ion channel, may be selected on the basisof the particular condition or site to be monitored. The targetingmoiety may comprise any of a number of different chemical entities. Inone embodiment, the targeting moiety is a small molecule. Moleculeswhich may be suitable for use as targeting moieties in the presentinvention include haptens, epitopes, and dsDNA fragments and analogs andderivatives thereof. Such moieties bind specifically to antibodies,fragments or analogs thereof, including mimetics (for haptens andepitopes), and zinc finger proteins (for dsDNA fragments). Nutrientsbelieved to trigger receptor-mediated endocytosis and therefore usefultargeting moieties include biotin, folate, riboflavin, carnitine,inositol, lipoic acid, niacin, pantothenic acid, thiamin, pyridoxal,ascorbic acid, and the lipid soluble vitamins A, D, E and K. Anotherexemplary type of small molecule targeting moiety includes steroidallipids, such as cholesterol, and steroidal hormones, such as estradiol,testosterone, etc.

In another embodiment, the targeting moiety may comprise a protein.Particular types of proteins may be selected based on knowncharacteristics of the target site or target cells. For example, theprobe can be an antibody either monoclonal or polyclonal, where acorresponding antigen is displayed at the target site. In situationswherein a certain receptor is expressed by the target cells, thetargeting moiety may comprise a protein or peptidomimetic ligand capableof binding to that receptor. Proteins ligands of known cell surfacereceptors include low density lipoproteins, transferrin, insulin,fibrinolytic enzymes, anti-HER2, platelet binding proteins such asannexins, and biological response modifiers (including interleukin,interferon, erythropoietin and colony-stimulating factor). A number ofmonoclonal antibodies that bind to a specific type of cell have beendeveloped, including monoclonal antibodies specific for tumor-associatedantigens in humans. Among the many such monoclonal antibodies that maybe used are anti-TAC, or other interleukin-2 receptor antibodies; 9.2.27and NR-ML-05 to the 250 kilodalton human melanoma-associatedproteoglycan; and NR-LU-10 to a pancarcinoma glycoprotein. An antibodyemployed in the present invention may be an intact (whole) molecule, afragment thereof, or a functional equivalent thereof. Examples ofantibody fragments are F(ab′)₂, Fab′, Fab, and F_(v) fragments, whichmay be produced by conventional methods or by genetic or proteinengineering.

Other preferred targeting moieties include sugars (e.g., glucose,fructose, galactose, mannose) that are recognized by target-specificreceptors. For example, instant claimed constructs can be glycosylatedwith mannose residues (e.g., attached as C-glycosides to a freenitrogen) to yield targeted constructs having higher affinity binding totumors expressing mannose receptors (e.g., glioblastomas andgangliocytomas), and bacteria, which are also known to express mannosereceptors (Bertozzi, C R and M D Bednarski Carbohydrate Research 223:243(1992); J. Am. Chem. Soc. 114:2242,5543 (1992)), as well as potentiallyother infectious agents. Certain cells, such as malignant cells andblood cells (e.g., A, AB, B, etc.), display particular carbohydrates,for which a corresponding lectin may serve as a targeting moiety.

In certain embodiments, the sensor may comprise an internalizing moietysuch as a polypeptide or small molecule. In certain embodiments, thesensor may comprise an internalizing polypeptide sequence, such asantepennepedia protein, mastoparan (T. Higashijima et al. (1990) J.Biol. Chem. 265:14176), melittin, bombolittin, delta hemolysin,pardaxin, Pseudomonas exotoxin A, clathrin, Diphtheria toxin, C9complement protein, or a fragment of one of the preceding proteins. Incertain embodiments, the internalizing moiety is not the HIVtransactivating (Tat) protein. In certain embodiments, the internalizingmoiety is bound to one or more of the other elements of the sensor. Inone embodiment of the invention, the internalizing moiety serves as thetargeting moiety (examples of such targeting moieties included herein).An internalizing moiety is capable of crossing a cellular membrane by,e.g., transcytosis, at a relatively high rate, and thereby promotescellular uptake or endosomal escape of molecules to which they areattached. In certain embodiments, the internalizing moiety crosses themembrane of intra- or extra-cellular vesicles such as endosomes orlysosomes. In certain such embodiments, sensors comprising internalizingmoieties are able to escape endosomal vesicles while sensors that lackinternalizing moieties are sequestered from the cellular medium insidesuch vesicles. In such embodiments, the sensor comprising aninternalizing moiety can be situated to monitor analyes in the cytosolof the cell. Certain internalizing polypeptides are also known tolocalize to the nucleus or other cellular structures. Thus a sensor ofthe present invention which includes such an internalizing peptidesequence may exhibit increased uptake by target cells relative tosensors that lack such a sequence.

The internalizing polypeptide may be part of the targeting moiety or aseparate element of the sensor. In one embodiment of the invention, theinternalizing polypeptide serves as the targeting moiety (see examplesabove of such targeting moieties). In another embodiment, theinternalizing polypeptide is covalently linked to one or more of theother elements of the sensor. For example, the internalizing polypeptidecan be linked to any one or more of the targeting moiety, the polymermatrix, the surface coating, and the surface modifier. The preferredlocation of an internalizing polypeptide in a sensor can be determined,e.g., by conducting in vitro assays using target cells, and detectingthe sensor signal that is incorporated into the cells or in specificregions within cells.

In one embodiment, the internalizing peptide is derived from thedrosophila antepennepedia protein, or homologs thereof. The 60 aminoacid long homeodomain of the homeo-protein antepennepedia has beendemonstrated to translocate through biological membranes and canfacilitate the translocation of heterologous polypeptides to which it iscouples. See for example Derossi et al. (1994) J Biol Chem269:10444-10450; Perez et al. (1992) J Cell Sci 102:717-722. Recently,it has been demonstrated that fragments as small as 16 amino acids longof this protein are sufficient to drive internalization. See Derossi etal. (1996) J Biol Chem 271:18188-18-193. The present inventioncontemplates a sensor comprising at least a portion of theantepennepedia protein (or homolog thereof) sufficient to increase thetransmembrane transport of the sensor, relative to the sensor alone, bya statistically significant amount.

While not wishing to be bound by any particular theory, it is noted thathydrophilic polypeptides may be also be physiologically transportedacross the membrane barriers by coupling or conjugating a component ofthe sensor to a transportable peptide which is capable of crossing themembrane by receptor-mediated transcytosis. Suitable internalizingpeptides of this type can be generated using all or a portion of, e.g.,a histone, insulin, transferrin, basic albumin, prolactin andinsulin-like growth factor I (IGF-I), insulin-like growth factor II(IGF-II) or other growth factors. For instance, it has been found thatan insulin fragment, showing affinity for the insulin receptor oncapillary cells, and being less effective than insulin in blood sugarreduction, is capable of transmembrane transport by receptor-mediatedtranscytosis. Preferred growth factor-derived internalizing peptidesinclude EGF (epidermal growth factor)-derived peptides, such asCMHIESLDSYTC (SEQ ID NO: 2) and CMYIEALDKYAC (SEQ ID NO: 3); TGF-beta(transforming growth factor beta)-derived peptides; peptides derivedfrom PDGF (platelet-derived growth factor) or PDGF-2; peptides derivedfrom IGF-I (insulin-like growth factor) or IGF-II; and FGF (fibroblastgrowth factor)-derived peptides. Hydrophilic polypeptides can be boundto a component of the sensor, or they can constitute the targetingmoiety.

Another class of translocating/internalizing peptides exhibitspH-dependent membrane binding. For an internalizing peptide that assumesa helical conformation at an acidic pH, the internalizing peptideacquires the property of amphiphilicity, e.g., it has both hydrophobicand hydrophilic interfaces. More specifically, within a pH range ofapproximately 5.0-5.5, an internalizing peptide forms an alpha-helical,amphiphilic structure that facilitates insertion of the moiety into atarget membrane. An alpha-helix-inducing acidic pH environment may befound, for example, in the low pH environment present within cellularendosomes. Such internalizing peptides can be used to facilitatetransport of sensors, taken up by an endocytic mechanism, from endosomalcompartments to the cytoplasm.

A preferred pH-dependent membrane-binding internalizing peptide includesa high percentage of helix-forming residues, such as glutamate,methionine, alanine and leucine. In addition, a preferred internalizingpeptide sequence includes ionizable residues having pKa's within therange of pH 5-7, so that a sufficient uncharged membrane-binding domainwill be present within the peptide at pH 5 to allow insertion into thetarget cell membrane.

A particularly preferred pH-dependent membrane-binding internalizingpeptide in this regard is aa1-aa2-aa3-EAALA(EALA)4-EALEALAA-amide (SEQID NO: 4), which represents a modification of the peptide sequence ofSubbarao et al. (Biochemistry 26:2964 (1987)). Within this peptidesequence, the first amino acid residue (aa1) is preferably a uniqueresidue, such as cysteine or lysine, that facilitates chemicalconjugation of the internalizing peptide to a targeting proteinconjugate. Amino acid residues 2-3 may be selected to modulate theaffinity of the internalizing peptide for different membranes. Forinstance, if both residues 2 and 3 are lys or arg, the internalizingpeptide will have the capacity to bind to membranes or patches of lipidshaving a negative surface charge. If residues 2-3 are neutral aminoacids, the internalizing peptide will insert into neutral membranes.

Yet other preferred internalizing peptides include peptides ofapo-lipoprotein A-1 and B; peptide toxins, such as melittin,bombolittin, delta hemolysin and the pardaxins; antibiotic peptides,such as alamethicin; peptide hormones, such as calcitonin,corticotrophin releasing factor, beta endorphin, glucagon, parathyroidhormone, pancreatic polypeptide; and peptides corresponding to signalsequences of numerous secreted proteins. In addition, exemplaryinternalizing peptides may be modified through attachment ofsubstituents that enhance the alpha-helical character of theinternalizing peptide at acidic pH.

Yet another class of internalizing peptides suitable for use within thepresent invention includes hydrophobic domains that are “hidden” atphysiological pH, but are exposed in the low pH environment of thetarget cell endosome. Upon pH-induced unfolding and exposure of thehydrophobic domain, the moiety binds to lipid bilayers and effectstranslocation of a covalently linked sensor into the cell cytoplasm.Such internalizing peptides may be modeled after sequences identifiedin, e.g., Pseudomonas exotoxin A, clathrin, or Diphtheria toxin.

Pore-forming proteins or peptides may also serve as internalizingpeptides herein. Pore forming proteins or peptides may be obtained orderived from, for example, C9 complement protein, cytolytic T-cellmolecules or NK-cell molecules. These moieties are capable of formingring-like structures in membranes, thereby allowing transport ofattached sensors through the membrane and into the cell interior.

Mere membrane intercalation of an internalizing peptide may besufficient for translocation of a sensor across cell membranes. However,translocation may be improved by attaching to the internalizing peptidea substrate for intracellular enzymes (i.e., an “accessory peptide”). Itis preferred that an accessory peptide be attached to a portion(s) ofthe internalizing peptide that protrudes through the cell membrane tothe cytoplasmic face. The accessory peptide may be advantageouslyattached to one terminus of a translocating/internalizing moiety oranchoring peptide. An accessory moiety of the present invention maycontain one or more amino acid residues. In one embodiment, an accessorymoiety may provide a substrate for cellular phosphorylation (forinstance, the accessory peptide may contain a tyrosine residue).

An exemplary accessory moiety in this regard would be a peptidesubstrate for N-myristoyl transferase, such as GNAAAARR (SEQ ID NO: 5)(Eubanks et al. (1988) Peptides. Chemistry and Biology, Garland Marshall(ed.), ESCOM, Leiden 566-69). In this construct, an internalizing,peptide would be attached to the C-terminus of the accessory peptide,since the N-terminal glycine is critical for the accessory moiety'sactivity. This hybrid peptide, upon attachment to a sensor component isN-myristylated and will be translocated across the cell membrane.

In certain embodiments the internalizing moiety comprises an aminegroup. In certain such embodiments, an amine group is bound to anycomponent of the sensor such as the polymer matrix, the surface coating,the surface modifier, the targeting moiety or any combination thereof.The amine group may have advantages in increasing release of nanosensorsinto the cytosol. One of the unique characteristics of endocytosis thatprevious studies and methods have exploited is the gradual decrease incompartment pH as the endosome passes from early stage to late stage andeventually forms a lysosome. The amine group is capable of exploitingthis phenomenon by protonating as the pH decreases. When the pH of theendosome drops to around 5 most of the amine groups will be protonated.This charge may be sufficient enough to lyse the membrane of theendosome and release the components.

In certain embodiments, the invention comprises methods of preparingsensors or sensor particles selective for an analyte, comprisingcombining a fluorescence source, a polymeric matrix, and ananalyte-sensitive component. In certain embodiments, theanalyte-sensitive component detects ions. In certain embodiments, theanalyte-sensitive component detects chelatable analytes, such asglucose. In certain embodiments, the method further comprises coatingthe polymer matrix with a coating layer, such as a biocompatiblecoating.

In certain embodiments, the subject sensors comprise a polymer matrix,e.g., as a body or substrate in which one or more functional componentsare disposed, e.g., within the coating layer. In certain embodiments,the polymer comprises poly(caprolactone) (PCL), ethylene vinyl acetatepolymer (EVA), poly(lactic acid) (PLA), poly(L-lactic acid) (PLLA),poly(glycolic acid) (PGA), poly(lactic acid-co-glycolic acid) (PLGA),poly(L-lactic acid-co-glycolic acid) (PLLGA), poly(D,L-lactide) (PDLA),poly(L-lactide) (PLLA), poly(D,L-lactide-co-caprolactone),poly(D,L-lactide-co-caprolactone-co-glycolide),poly(D,L-lactide-co-PEO-co-D,L-lactide),poly(D,L-lactide-co-PPO-co-D,L-lactide), polyalkyl cyanoacralate,polyurethane, poly-L-lysine (PLL), hydroxypropyl methacrylate (HPMA),polyethyleneglycol, poly-L-glutamic acid, poly(hydroxy acids),polyanhydrides, polyorthoesters, poly(ester amides), polyamides,poly(ester ethers), polycarbonates, silicones, polyalkylenes such aspolyethylene, polypropylene, and polytetrafluoroethylene, polyalkyleneglycols such as poly(ethylene glycol) (PEG), polyalkylene oxides (PEO),polyalkylene terephthalates such as poly(ethylene terephthalate),polyvinyl alcohols (PVA), polyvinyl ethers, polyvinyl esters such aspoly(vinyl acetate), polyvinyl halides such as poly(vinyl chloride)(PVC), polyvinylpyrrolidone, polysiloxanes, polystyrene (PS),polyurethanes, derivatized celluloses such as alkyl celluloses,hydroxyalkyl celluloses, cellulose ethers, cellulose esters, nitrocelluloses, hydroxypropylcellulose, carboxymethylcellulose, polymers ofacrylic acids, such as poly(methyl(meth)acrylate) (PMMA),poly(ethyl(meth)acrylate), poly(butyl(meth)acrylate),poly(isobutyl(meth)acrylate), poly(hexyl(meth)acrylate),poly(isodecyl(meth)acrylate), poly(lauryl(meth)acrylate),poly(phenyl(meth)acrylate), poly(methyl acrylate), poly(isopropylacrylate), poly(isobutyl acrylate), poly(octadecyl acrylate) (jointlyreferred to herein as “polyacrylic acids”), and copolymers and mixturesthereof, polydioxanone and its copolymers, polyhydroxyalkanoates,poly(propylene fumarate), polyoxymethylene, poloxamers,poly(ortho)esters, poly(butyric acid), poly(valeric acid),poly(lactide-co-caprolactone), trimethylene carbonate,polyvinylpyrrolidone, and the polymers described in Shieh et al., 1994,J. Biomed. Mater. Res., 28, 1465-1475, and in U.S. Pat. No. 4,757,128,Hubbell et al., U.S. Pat. Nos. 5,654,381; 5,627,233; 5,628,863;5,567,440; and 5,567,435. Other suitable polymers includepolyorthoesters (e.g. as disclosed in Heller et al., 2000, Eur. J.Pharm. Biopharm., 50:121-128), polyphosphazenes (e.g. as disclosed inVandorpe et al., 1997, Biomaterials, 18:1147-1152), andpolyphosphoesters (e.g. as disclosed in Encyclopedia of Controlled DrugDelivery, pp. 45-60, Ed. E. Mathiowitz, John Wiley & Sons, Inc. NewYork, 1999), as well as blends and/or block copolymers of two or moresuch polymers. The carboxyl termini of lactide- and glycolide-containingpolymers may optionally be capped, e.g., by esterification, and thehydroxyl termini may optionally be capped, e.g., by etherification oresterification. In certain embodiments, the polymer comprises orconsists essentially of polyvinyl chloride (PVC), polymethylmethacrylate (PMMA) and decyl methacrylate or copolymers or anycombination thereof.

In certain embodiments, the polymer comprises a biocompatible polymer,e.g., selected from poly(caprolactone) (PCL), ethylene vinyl acetatepolymer (EVA), poly(ethylene glycol) (PEG), poly(vinyl acetate) (PVA),poly(lactic acid) (PLA), poly(glycolic acid) (PGA),poly(lactic-co-glycolic acid) (PLGA), polyalkyl cyanoacrylate,polyethylenimine,dioleyltrimethyammoniumpropane/dioleyl-sn-glycerolphosphoethanolamine,polysebacic anhydrides, polyurethane, nylons, or copolymers thereof. Inpolymers including lactic acid monomers, the lactic acid may be D-, L-,or any mixture of D- and L-isomers. In certain aspects, thebiocompatible polymer comprises a PEG-lipid. In certain suchembodiments, the lipid tail self-inserts into the lipophilic polymermatrix during fabrication, leaving the PEG headgroup on the surface ofthe sensor, e.g., to provide a hydrophilic, biocompatible coating thatcan be penetrated by the analyte. In certain embodiments, differentchemical moieties, such as amines, can be put on the surface or furthermodified to attach antibodies or other recognition units.

The terms “biocompatible polymer” and “biocompatibility” when used inrelation to polymers are art-recognized. For example, biocompatiblepolymers include polymers that are neither themselves toxic to the host(e.g., a cell, an animal, or a human), nor degrade (if the polymerdegrades) at a rate that produces monomeric or oligomeric subunits orother byproducts at toxic concentrations in the host. Consequently, incertain embodiments, toxicology of a biodegradable polymer intended forintracellular or in vivo use, such as implantation or injection into apatient, may be determined after one or more toxicity analyses. It isnot necessary that any subject composition have a purity of 100% to bedeemed biocompatible. Hence, a subject composition may comprise 99%,98%, 97%, 96%, 95%, 90%, 85%, 80%, 75% or even less of biocompatiblepolymers, e.g., including polymers and other materials and excipientsdescribed herein, and still be biocompatible.

The polymer matrix of the sensor may comprise a plasticizer, such asdioctyl sebacate (DOS), o-nitrophenyl-octylether, dimethyl phthalate,dioctylphenyl-phosphonate, dibutyl phthalate, hexamethylphosphoramide,dibutyl adipate, dioctyl phthalate, diundecyl phthalate, dioctyladipate, dioctyl sebacate, or other suitable plasticizers. In certainembodiments, the plasticizer is poly(glycerol sebacate), PGS.

In certain embodiments, e.g., particularly where the polymer isbiocompatible, a biocompatible plasticizer is used. The term“biocompatible plasticizer” is art-recognized, and includes materialswhich are soluble or dispersible in the relevant polymer, which increasethe flexibility of the polymer matrix, and which, in the amountsemployed, are biocompatible. Suitable plasticizers are well known in theart and include those disclosed in U.S. Pat. Nos. 2,784,127 and4,444,933. Specific plasticizers include, by way of example, acetyltri-n-butyl citrate (c. 20 weight percent or less), acetyltrihexylcitrate (c. 20 weight percent or less), butyl benzyl phthalate,dibutylphthalate, dioctylphthalate, n-butyryl tri-n-hexyl citrate,diethylene glycol dibenzoate (c. 20 weight percent or less) and thelike.

In certain embodiments, the sensor or sensor particle comprises acoating layer, such as a barrier layer or a biocompatible coating. Incertain such embodiments, the biocompatible coating comprises abiocompatible polymer.

Sensors of the invention typically comprise a fluorescent component,such as one or more quantum dots or one or more fluorescent dyes. Invarious embodiments, a fluorescent dye can be used as a source offluorescence in place of a quantum dot or vice versa. In certainembodiments, a sensor comprises at least one quantum dot and/or at leastone fluorescent dye, a chromophore, and a polymer matrix. In certainembodiments, the photons emitted by the quantum dot and/or fluorescentdye in an excited state are absorbed by a chromophore in the presence ofthe analyte but not absorbed by a chromophore in the absence of theanalyte. In certain other embodiments, the photons emitted by thequantum dot and/or fluorescent dye in an excited state are absorbed by achromophore in the absence of the analyte but not absorbed by achromophore in the presence of the analyte.

Quantum dots are fluorescent semiconductor nanocrystals having acharacteristic spectral emission, which is tunable to a desired energyby selection of the particle size, size distribution and composition ofthe semiconductor nanocrystal. The emission spectra of a population ofquantum dots have linewidths as narrow as 25-30 nm, depending on thesize distribution heterogeneity of the sample population, and lineshapesthat are symmetric, gaussian or nearly gaussian with an absence of atailing region. Advantageously, the range of excitation wavelengths ofthe quantum dots is broad. Consequently, this allows the simultaneousexcitation of varying populations of quantum dots in a system havingdistinct emission spectra with a single light source, e.g., in theultraviolet or blue region of the spectrum. Fluorescent dyes may includeany fluorescent compound, such as a dye. Preferably, the emissions of afluorescent dye used as a fluorescence source are not substantiallyaffected by the analyte or other components of test solutions.

In certain embodiments, quantum dots of the sensors described hereinare, for example, inorganic crystallites between 1 nm and about 1000 nmin diameter, preferably between about 2 nm and about 50 nm, morepreferably about 5 nm to 20 nm, such as about 6, 7, 8, 9, 10, 11, 12,13, 14, 15, 16, 17, 18, 19, or 20 nm. Such quantum dots include a “core”of one or more first semiconductor materials, and which may besurrounded by a “shell” of a second semiconductor material. Asemiconductor nanocrystal core surrounded by a semiconductor shell isreferred to as a “core/shell” semiconductor nanocrystal. The surrounded“shell” will most preferably have a bandgap greater than the bandgap ofthe core material and can be chosen so to have an atomic spacing closeto that of the “core” substrate. The core and/or the shell material canbe a semiconductor material including, but not limited to, those of thegroup II-VI (ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, MgTe andthe like) and III-V (GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AlAs,AlP, AlSb, AlS, and the like) and IV (Ge, Si, Pb and the like)materials, and an alloy thereof, or a mixture thereof.

In certain embodiments, a sensor comprises exactly one quantum dot,while in other embodiments, a sensor comprises more than one quantumdot, for example, 2, 3, 4, or 5 quantum dots. In certain embodimentswherein the sensor comprises more than one quantum dot, the sensorcomprises two or more types of quantum dots, each type having a distinctemission wavelength, e.g., independently selected from, for example,490, 520, 545, 560, 580, 620, 655 nm. The availability of two distinctwavelength emissions (e.g., one or more quantum dots of wavelength 545nm and one or more quantum dots with emission wavelength of 655 nm) mayallow improvements in recording of changes in ion concentration by usingthe ratio of the two distinct signals. Fluctuations in fluorescence thatare common to both signals should theoretically cancel in a ratio. Thedetectable fluorescence emission of the quantum dot particles mayfluctuate depending on variables including number of quantum dots,quantum dot location within the cell, photobleaching, and possiblechanges in excitation light intensity, all effects that can occur slowlyand are not related to ion presence or concentration. Therefore, effectsincluding number of quantum dots, quantum dot location within the cell,photobleaching, and possible changes in excitation light intensity maybe attenuated.

The quantum dot of the sensor particle may be modified with a surfacemodifier, e.g., to alter one or more properties of the sensor particle,such as solubility, biocompatibility, or hydrophilicity/hydrophobicity.In certain embodiments, the surface modifier comprises one or moreligands that can bind reversibly with the quantum dot, while in otherembodiments, the surface modification may be essentially irreversible.In certain embodiments, the surface modifier improves the lipophilicityof the quantum dot. In certain such embodiments, the ligand comprises analkane such as decane-thiol.

In certain embodiments, the fluorescence signal of the quantum dot orfluorescent dye may trigger a detectable event within the cell. Forexample, fluorescence may in turn excite a secondary dye or quantum dotin the particle that easily generates reactive oxygen species (ROS). TheROS would then attack the cell, effectively stimulating necrosis (celldeath), which may then be detected either visually or using markerssensitive to cell death. Alternatively, instead of including a secondarycomponent within the particle, another particle may be added to the cellor cell culture. This additional particle may, for example, comprise aphoto-degradable polymer membrane. When the primary sensor fluoresces,the emitted light will rupture the secondary particle, releasing itscontents. The contents may, for example, be a drug that is therapeuticor apoptotic, e.g., triggering another detectable event.

In other exemplary embodiments, sensors comprise sensor particles forthe detection of chelatable analytes, e.g., glucose. These sensorparticles comprise a polymer matrix, a surface coating, moieties whichbind a chelatable analyte, and a component that emits or absorbs photonsof a particular wavelength either in the presence of absence of thechelatable analyte. In an exemplary embodiment, a chromophore absorbsphotons of one wavelength when bound to the moieties of the sensor andanother wavelength when unbound from the moieties. When thechromophore-bound moieties are exposed to the chelatable analyte, thechromophore is released and the chelatable analyte binds to themoieties. The free chromophore appears as a different color than thebound chromophore, a change which can be monitored visually or withspectrophotometric instrumentation. In an alternate exemplaryembodiment, wherein the inner-filter effect is employed, the sensorparticle of the preceding embodiment further comprises a fluorescent dyeand/or quantum dot. The fluorescent dye and/or quantum dot absorbs abroad range of wavelengths and emits photons of a narrow range ofwavelengths. The fluorescence emitted by the fluorescent component iseither absorbed or not absorbed depending on the presence of thechelatable analyte. For example, when the chelatable analyte is bound tothe moieties of the sensor, the fluorescence of the quantum dot isabsorbed while no absorbance occurs in the absence of the chelatableanalyte.

In certain embodiments, the sensor particle for detecting the presenceof chelatable analytes comprises a surface coating and a polymer matrixcomprising a polymer including moieties that bind the chelatable analyteand a chromophore associated with the polymer matrix that binds to themoieties in the absence of the chelatable analyte. In certainembodiments, the chelatable analyte is glucose and the moieties bindglucose and the chromophore reversibly and competitively. In anexemplary embodiment, the sensor particle 3 comprises a coating 28 and apolymer matrix with moieties 1 that can bind both a chromophore 2 andglucose 5 (FIG. 2). In a first mode, the moieties 1 are bound to achromophore 2 and the chromophore, in its bound mode, absorbs photons ata first wavelength 4. In a second mode, when the sensor particle 3 iscontacted with glucose 5, the glucose 5 binds to the moieties 1,displacing the chromophore 2 which, in its unbound state, absorbsphotons at a second wavelength 6. In certain embodiments, the sensor 3is monitored visually to determine a change in the color of thechromophore 2. In certain embodiments, the sensor 3 is monitored withspectrophotometric instrumentation to determine the emission spectra ofthe chromophore 2.

In certain embodiments, the sensor particle for detecting the presenceof a chelatable analyte comprises a surface coating, a fluorescentcomponent, a polymer matrix comprising a polymer including moieties thatbind the chelatable analyte and a chromophore associated with thepolymer matrix that binds to the moieties in the absence of thechelatable analyte. In certain embodiments, the sensor particle emitsphotons with an inner filter effect. The inner-filter effect has beendocumented as a way to increase the signal intensity and concomitantsensitivity of ion-selective optical sensors (optode). In brief, asecondary, inert fluorescent component is added to the polymer matrix ofthe optode. When the concentration of analyte in the optode changes, thefluorescence intensity of the inert dye itself does not respond, howeverthe absorbance of the sensor does. Because the fluorescence emission hasbeen carefully chosen to overlap with the absorbance spectrum of thesensor, the emission from the inert dye is then absorbed by the sensor.The attenuation of the fluorescence output of the inert dye is thereforedirectly related to the concentration of the ion of interest insolution.

In certain embodiments, the chelatable analyte is glucose and themoieties bind glucose and the chromophore reversibly and competitively.In certain embodiments, the fluorescent component is selected from oneor more quantum dots and/or fluorescent dyes 7. In certain suchembodiments, a sensor particle 3 comprises a coating 28 and afluorescent component 7, and a polymer matrix with moieties 1 that canbind both a chromophore 2 and glucose 5. In certain such embodiments,the fluorescent component 7 absorbs a broad range of wavelengths ofphotons but emits a narrow range of wavelengths of photons. Thefluorescent component 7 is activated by exciting with a light source,e.g., UV light. The fluorescence emitted from the excited fluorescentcomponent 7 is either absorbed by a component of the sensor, e.g., thechromophore 2 or the glucose-moiety complex, or emitted from the sensor3 without being attenuated. In certain embodiments, photons 4 of thefluorescent component 7 are absorbed when the chromophore 2 is bound tothe moieties 1 (FIG. 4, left). In certain such embodiments, the absenceof fluorescence emitted from the sensor particle 3 indicates an absenceof glucose molecules 5, i.e. glucose molecules are not bound to themoieties of the sensor. In such embodiments, when glucose 5 isintroduced, the moieties 1 bind glucose 5, releasing the chromophore 2.The photons 4 of the fluorescent component 7 are no longer absorbed by acomponent of the sensor, FIG. 4, right. By detecting the emittedphotons, the amount of bound glucose can be calculated relative to astandard.

In certain embodiments, a component of the sensor, e.g., the chromophore2 or the glucose-moiety complex, absorbs photons 4 of the fluorescentcomponent 7 when unbound from the moieties 2 (FIG. 3, right). In certainsuch embodiments, the detection of photons 4 from the sensor 3 indicatesthe absence of glucose 5, i.e., glucose molecules are not bound to themoieties of the sensor. In certain such embodiments, when the sensor 3is contacted with glucose 5, the moieties 1 release the chromophore 2and bind glucose 5. In such embodiments, the photons 4 of thefluorescent component 7 are not absorbed when glucose 5 is bound to themoieties 1 such that the detection of photons 4 emitted from the sensorparticle 3 indicates the presence of glucose 5.

In certain embodiments, the sensors of the present invention may be usedto detect and measure the presence of a wide variety of chelatableanalytes, e.g., sugars and related compounds, in a solution, in vitro orin vivo. The sensor may be located within a cell, i.e., intracellular,or exterior to a cell, i.e., extracellular. In certain embodiments, thesensor is in contact with the cell membrane such as within a cell orexterior to a cell. Exemplary chelatable analytes for detection by thesensor of the present invention include sugars such as glucose, mannose,and other monosaccharides, sialic acid, lactic acids, aminosugars, suchas glucosamine, disaccharides, trisaccharides, oligosaccharides,sugar-amino acids, sugar-peptides and glycoproteins. Other exemplarychelatable analytes include, but are not limited to, glycerol, dopamine,catechols, ascorbic acid, polyols, diols such as 1,4-anhydroerythritoland ethylene glycol. The concentration range of chelatable analyteswhich is typically of interest in biological samples is 0-25 mM, such asfrom 5-20 mM, such as from 5-10 mM, such as from 0-5 mM.

In certain embodiments, the moieties that bind the chelatable analytescomprise a dihydroxide component, e.g., boron and alkali earthdihydroxides. Complexation of sugars, for example, with boron and alkaliearth dihydroxides has been reported in, among other sources, [S. A.Barker et al., Carbohydrate Research, 26 (1973) 33-40; N. Roy et al.,Carbohydrates Research, 24 (1972) 180-183]. A variety of differentboronic acids, having the structure RB(OH)₂ may be used to chelate theanalyte. R can be, for example, an aryl or a saturated or unsaturatedalkyl moiety, either of which can be substituted or unsubstituted andcan contain one or more heteroatoms, e.g., N, S, O, P, B, F, Br. Incertain embodiments, a boronic ester is used to chelate the analyte.Boronic esters have the molecular formula RB(OR′)₂ wherein R′ istypically an alkyl group and R can be defined as above. Under aqueousconditions, many boronic esters hydrolyze to form boronic acids.Therefore, OR′ groups that hydrolyze to OH are of use in the presentinvention. The two R′ groups of the ester may be linked to form a cyclicstructure, e.g., —CH₂CH₂—. In certain embodiments, the moieties areselected from one ore more aromatic or aliphatic boronic esters. Incertain aspects, boronic acids are appended with substituents thataffect the pKa such as electron withdrawing groups or electron donatinggroups. In certain embodiments the pK_(a) of the boronic acid willchange the dynamic range of the sensor. In certain embodiments thedynamic range of the sensor relates to the affinity for an analyte, suchas glucose. In certain embodiments, the moieties are selected from oneor more aromatic or aliphatic boronic acids. Exemplary boronic acidmoieties of the invention include phenyl boronic acid, butyl boronicacid, (3,5-dichlorophenyl)boronic acid,[3,5-bis(trifluoromethyl)phenyl]boronic acid, and (4-bromophenyl)boronicacid.

In certain embodiments, the moieties of the sensor which chelate theanalytes comprise a metal ion. The ability of sugars, for example, andother molecules to form chelate complexes with metal ions in aqueoussolution is well known (general review by: Whitfield, D. M. et al.,“Metal coordination to carbohydrates. Structure and Function,” Coord.Chem. Reviews 122, 171-225 (1993) and Angya, S. J. Complexes of MetalCations with Carbohydrates in Solution, in “Advances in CarbohydrateChemistry and Biochemistry,” Academic Press, Inc. 1989, pp. 1-4). Thecomplexation of Cu(II) with various sugar a-amino acids is described byM. Angeles Diaz-Diez et al., Transition Met. Chem. 20, 402-405, 1995.Sugar-α-amino acid compounds will also form complexes with Co(II),Ni(II), Zn(II) and Cd(II) (M. Angeles Diaz-Diez et al., J. Inorg.Biochem. 56, 243-247, 1994). Additionally, complexes of various sugarswith vanadium, molybdenum, tungsten, aluminum, iron, barium, magnesium,and strontium are known (Sreedhara, A. et al., Carbohydrate Res. 264,227-235, 1994; Caldeira, M. M. et al., Inorg. Chim. Acta. 221, 69-77,1994; Tonkovic, M. and Bilinski, H., Polyhedron 14, 1025-1030, 1995;Nagy, L. et al., Inorg. Chim. Acta. 124, 55-59, 1986; Tajmir-Riahi, H.A., Inorg. Chim. Acta. 119, 227-232, 1986; and Tajmir-Riahi, H. A., J.Inorg. Biochem., 24, 127-136, 1985.

In certain embodiments, the moieties that bind the chelatable analytesare covalently conjugated to the polymer matrix, the surface coating, orboth, for example, through a linker molecule. In an exemplaryembodiment, the moieties comprise aryl boronic acids which arecovalently conjugated to the polymer matrix through ester linkagesoriginating at an aryl atom or the aryl boronic acid. Other exemplarylinkages include amides, ethers, sulfonates, thioethers, thioesters andcarbonates. In certain embodiments, the moieties are covalently bound tothe polymer matrix through a bond such as a single or double bond. Incertain exemplary embodiments, the aryl boronic acids are covalentlybound to the polymer matrix through a single bond originating from anaryl atom or the aryl boronic acid.

In certain embodiments, the chromophore of the sensor is any moleculethat binds reversibly to the moieties of the sensor, e.g., thechromophore alizarin binds boronic acids, and absorbs photons of thefluorescent component in a first state and does not absorb photons ofthe fluorescent component in a second state. The states of thechromophore include bound to the moieties and unbound from the moieties.For example, the chromophore alizarin absorbs at a first wavelength whenunbound and a second wavelength when bound to a boronic acid. Thefollowing depits an exemplary interaction between alizarin and a boronicacid:

certain embodiments, the chromophore, e.g., alizarin, is selected fromany dye that binds boronic acid moieties, preferably havingabsorbance/fluorescence properties that differ in the bound vs. the freestate. When a suitable chelatable analyte is present, the boronic acidreleases the chromophore and binds the analyte. Additional FDA approveddyes and colored drugs are described in the Code of Federal Regulations(CFR) for Food and Drugs (see Title 21 of CFR chapter 1, parts 1-99). Awide variety of chromophores and fluorescence sources may be used, e.g.,paired so that the absorbance wavelength of the unbound chromophoresubstantially matches the wavelength of the fluorescent component'sphoton emissions, e.g., so as to absorb the emissions in an unboundstate. The table below lists a number of suitable chromophores, theirChemical Abstract Service (CAS) Registration Numbers, colors andabsorption maxima. In certain embodiments, the chromophore isderivatized in such a manner that it can bind with the chelating moietyof the sensor.

Chromophore CAS Reg. No. Color Abs. Max. Yellow No. 5 1934-21-0 yellow428 β-carotene 7235-40-7 orange 466 Rifampin 3292-46-1 red 475 YellowNo. 6 2783-94-0 yellow 480 Tetracycline 60-54-8 yellow N/A Red No. 4025956-16-6 red 502 Red No. 3 16423-68-0 red 524 Blue No. 2 860-22-0 blue610 Evan's blue 314-13-6 blue 610 Green No. 3 2353-45-9 green 628 BlueNo. 1 2650-18-2 blue 630 Methylene blue 7220-79-3 Blue 668/609Indocyanine green 3599-32-4 Green 800 (mostly IR)

In certain embodiments, the chromophore is covalently conjugated to thepolymer matrix and/or the surface coating and comprises a reactive sitethat binds reversibly with the chelatable analyte selective moieties. Inan exemplary embodiment, the chromophore is alizarin, and the alizarinis covalently bound to the polymer matrix and/or the surface coatingthrough one or more linkers or bonds. In certain embodiments, the linkeris an ester amide, ether, sulfonate, thioether, carbonate or thioesteroriginating from an aromatic carbon of the alizarin. In certainembodiments, the chromophore is covalently conjugated through one ormore bonds to the polymer matrix and/or the surface coating. In certainembodiments, the bonds or linkages between the chromophore and thepolymer matrix and/or the surface coating does not interfere with theability of the chromophore to bind to the chelatable analyte. Forexample, in the case of alizarin, the linkages or bonds to the polymermatrix and/or the surface coating originates from a ring of thepolycyclic ring system that does not bear the hydroxy groups. In certainsuch embodiments, the hydroxyl groups of the alizarin are unimpeded frominteracting with the chelatable analyte.

In certain embodiments, the sensor particle for detecting the presenceof glucose comprises: a quantum dot, a surface coating, a polymer matrixcomprising a polymer appended with moieties that selectively bindglucose, a chromophore associated with the polymer matrix that binds themoieties in the absence of glucose, and a polymer coating, such as abiocompatible coating.

In certain embodiments, additives to the polymer matrix and/or thecoating make the extraction of the analyte (e.g., glucose) into thepolymeric matrix more efficient. In certain embodiments, the addition ofamine-based additives to the matrix lowers the effective dynamic rangeof the sensor particles. In certain embodiments, the addition of aminesto the polymer matrix increases the affinity of the polymer matrix forthe analyte, e.g., glucose.

In an exemplary embodiment, sensors are ionic sensors. Emissions fromthe sensor indicate the ion concentrations and fluxes from the cell. Incertain aspects, the sensors comprise a polymer, a fluorescentsemiconductor nanocrystal (also known as a quantum dot™ particle) or afluorescent dye that fluoresces at a first wavelength, and achromoionophore that absorbs photons of the first wavelength in onestate and does not absorb photons of the first wavelength in a secondstate. In monitoring ionic analytes, the chromoionophore changes statein response to proton concentration (i.e., the protonatedchromoionophore is one state while the deprotonated chromoionophore is asecond state). To monitor a specific analyte, an ionophore thatselectively associates with specific ions or groups of ions is includedin the sensor. Once the ionophore associates with a cationic analyte(e.g., Na⁺ associates with a Na⁺-selective ionophore), for example,protons are displaced from the sensor to equilibrate charge, alteringthe state of the chromoionophore. The fluorescence emitted from thesensor indicates the state of the chromoionophore which correlates tothe presence and/or concentration of the ionic analyte. Sensors that usefluorescent dyes instead of quantum dots are disclosed in PCTPublication No. WO2008/063151 A2, the disclosure of which isincorporated herein by reference.

For ion-detecting sensors, the ionophore is a compound, typically anelectrically neutral compound, that associates (e.g., forms a complex,chelate, or other non-covalent association) with a target ion, and isselective for the target ion relative to other ions. The ionophore isselected to be lipid-soluble and does not emit light in the visiblespectrum in either of its complexed and non-complexed states. In certainaspects, the ionophore of the mixture included herein is chosen toselectively bind an ionic analyte, for example, K⁺, Na⁺, Ca²⁺, H⁺, Ba²⁺,Li⁺, Cl⁻, NH₄ ⁺, or NO₃ ⁻. Potassium ion ionophores include, forexample, valinomycin, crown ethers, e.g., dimethyldibenzo-30-crown-10,dicyclohexyl-18-crown, dimethyldicyclohexyl-18-crown-6, tetraphenylborate, tetrakis(chlorophenyl)borate. Sodium ion ionophores include, forexample, methyl monensin,N,N′,N″-triheptyl-N,N′,N″-trimethyl-4,4′,4″-propylidintris-(3-oxabutyramide),N,N,N′,N′-tetracyclohexyl-1,2-phenylenedioxydiacetamide,4-octadecanoyloxymethyl-N,N,N′,N′-tetracyclohexyl-1,2-phenylenedioxydiacetamide,bis[(12-crown-4)methyl]dodecylmethylmalonate. Exemplary calcium ionionophores include, for example, bis(didecylphosphate),bis(4-octylphenylphosphate),bis(4-(1,1,3,3-tetramethylbutyl)phenylphosphatetetracosamethylcyclododecasiloxane,N,N′-di(11-ethoxycarbonyl)undecyl)-N,N′,4, 5-tetramethyl-3,6-dioxaoctanediamide. Barium ion ionophores include, for example, calciumdi(2-ethylhexyl)phosphate+decan-1-ol, barium complex ofnonylphenoxypoly(ethyleneoxy)ethanol in ortho-nitrodiphenyl ether.Chloride ion ionophores include, for example,{μ-[4,5-dimethyl-3,6-bis(octyloxy)-1,2-phenylene]}bis(trifluoroacetato-O)dimercuri(ETH 9009),{μ-[4,5-dimethyl-3,6-bis(dodecyloxy)-1,2-phenylene]}bis(mercurychloride) (ETH 9033), 5,10,15,20-tetraphenyl-21H,23H-porphin manganese(III) chloride (MnTPPCl), tributyltin chloride (TBTCl) and trioctyltinchloride (TOTCl). Bicarbonate ion ionophores of the invention include,for example, quaternary ammonium ion exchangerp-octodecyloxy-meta-chlorophenyl-hydrazone-mesoxalonitrile. Ammonium ionionophores include, for example, nonactin and monactin. Nitrate ionionophores include, for example, tridodecylhexadecylammoniumnitrate+n-octyl-ortho-nitrophenyl, 1:10 phenanthroline nickel (II)nitrate+para-nitrocymene. Lithium ion ionophores include, for example,N,N′-diheptyl-N,N′, 5,5-tetramethyl-3,7-dioxononanediamide),12-crown-4,6,6-dibenzyl-14-crown-4.

A chromoionophore is an ionophore that changes its optical properties inthe visible spectrum depending on the state of complexation.Chromoionophores for use in sensors are typically proton-sensitive dyesthat change absorbance (and fluorescence in many cases) depending on thedegree of protonation, although chromoionophores that change absorbancein response to other ions can also be used. The chromoionophores arepreferably highly lipophilic to inhibit leaching from the sensor matrix.Suitable chromoionophores include Chromoionophore I (i.e.,9-(Diethylamino)-5-(octadecanoylimino)-5H-benzo[a]phenoxazine),Chromoionophore II (i.e.,9-Dimethylamino-5-[4-(16-butyl-2,14-dioxo-3,15-dioxaeicosyl)phenylimino]benzo[a]phenoxazine)and Chromoionophore III (i.e.,9-(Diethylamino)-5-[(2-octyldecyl)imino]benzo[a]phenoxazine).Chromoionophore II exhibits light absorbance peaks at 520 nm and 660 nmand a fluorescent emission peak at 660 nm. Chromoionophore III has lightabsorbance peaks at 500 nm and 650 nm and fluorescent emission peaks at570 nm and 670 nm.

An ion-detecting sensor may comprise an additive, e.g., to embed chargesites within the polymer phase and/or to help enforce charge neutralitywithin the sensor. For sensors targeting cations, the additive can beany inert and preferably lipophilic component that has a negative chargeassociated with it. For sensors targeting anions, the additive ispositively charged and preferably lipophilic. The additive allows thepolymer phase to carry a corresponding amount of oppositely chargedparticles while maintaining overall charge neutrality of the sensor. Theconcentration ratio of additive to chromoionophore is preferably 1:1,thereby allowing the chromoionphore to become completely protonated ordeprotonated. One suitable additive for sensors targeting negative ionsis potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (KTFPB). Thelipophilic, anionic component TFPB molecules are retained by the polymerphase, and the potassium ions are either complexed by the ionophore orexpelled into the sample solution through diffusion. In one particularimplementation, the sensor film is composed of a suspension producedfrom about 60 mg of DOS, 30 mg of PVC, and up to about 5 mg of additive,ionophore, and chromoionophore.

In a sample solution, the sensor continuously extracts or expels, forexample, analyte cations depending on ion activity in the samplesolution. The ion activity of a sample solution can be monitored byobserving the fluorescence of a sensor of the invention in the samplesolution. As depicted in FIG. 14, the sensor with a coating 28 mayfluoresce in the presence of a cationic analyte 21, and not in theabsence of said analyte, Mode A. In such embodiments, thechromoionophore 24, of the sensor absorbs photons 25, of a quantum dot26, when the cationic analyte 21 is not bound to the ionophore 22. Insuch embodiments, the wavelength of photons 25 emitted from the quantumdot 26 when excited with a light source such as UV or visible light fallwithin the absorbance range, e.g., maximum absorbance range, of thechromoionophore 24 bound to a proton 23, such that the fluorescence ofthe quantum dot is attenuated or completely undetectable from outside ofthe polymer matrix 20 (Mode A, sensor on the left). As the target ion 21increases in concentration in solution, the ions 21 are drawn throughthe coating 28 into the polymer matrix 20 to bind with the ion-selectiveionophore 22. To maintain charge neutrality within the polymer matrix20, protons 23 dissociate from the chromoionophore 24 in the sensor anddiffuse out of the polymer matrix 20 through the coating 28 into thesample solution, altering the absorbance properties of thechromoionophore 24. The deprotonated chromoionophore 24 has a shiftedabsorbance region such that the photons 25 emitted by the quantum dot 26are no longer absorbed by the chromoionophore 24 (Mode A, sensor on theright). The sensor then emits a detectable signal indicating thepresence of the analyte.

In an alternate embodiment for detecting cationic analytes, FIG. 14,Mode B, the quantum dot 27 of the sensor emits photons 25 that are notabsorbed by the chromoionophore 24 in the absence of the cationicanalyte 21. In certain such embodiments, the chromoionophore 24 absorbsphotons 25 of the quantum dot 27 when the cationic analyte 21 is boundto the ionophore 22. In such embodiments, the wavelength of emittedphotons 25 from the quantum dot 27 when excited with a light source suchas UV or visible light, do not fall within the absorbance range, e.g.,the maximum absorbance range, of the chromoionophore 24 when bound to aproton 23, such that the fluorescence of the quantum dot 27 is emittedfrom the polymer matrix 20 (Mode B, sensor on the left). As the targetion 21 increases in concentration in solution, the ions 21 are drawnthrough the coating 28 into the polymer matrix 20 to bind with theion-selective ionophore 22. To maintain charge neutrality within thepolymer matrix 20 of the sensor, protons 23 dissociate from thechromoionophore 24 of the sensor and diffuse out of the polymer matrix20 through the coating 28 into the sample solution, altering theabsorbance properties of the chromoionophore 24. The deprotonatedchromoionophore 24 has a shifted absorbance region such that the photons25 emitted by the quantum dot 27 are absorbed by the chromoionophore 24(Mode B, sensor on the right). The sensor signal is attenuated orextinguished indicating the presence of the analyte.

In an embodiment for detecting anionic analytes, depicted in FIG. 15,Mode A, the ionophore 22 of the sensor selectively binds an anionicanalyte 28 or a group of anionic analytes. In certain such embodiments,the sensor comprises a chromoionophore 24 which absorbs photons 25emitted from the quantum dot 26 upon excitation, e.g., by light such asUV or visible, when the ionic analyte 28 is not bound to the ionophore22 of the sensor. In such a state, the wavelengths of the photons 25emitted by the quantum dot 26 are within the absorbance range, e.g., themaximum absorbance range, of the chromoionophore 24 in a deprotonatedstate and the fluorescence detected outside of the polymer matrix 20 isattenuated or undetectable from outside the sensor (FIG. 14, Mode A,sensor on the left). As the target ion 28 increases in concentration inthe sample solution, the anionic analyte 28 is drawn into the polymermatrix 20 through the coating 28, binding with the ion-selectiveionophore 22. To maintain charge neutrality within the polymer matrix20, protons 23 diffuse from the sample solution into the polymer matrix20 through the coating 28, protonating the chromoionophores 24 such thatthe absorbance properties are altered. The protonated chromoionophore 24has a shifted absorbance region such that the photons 25 of the quantumdot 26 are not absorbed by the chromoionophore 24 (FIG. 14, Mode A,sensor on the right). The sensor emits a detectable fluorescence signalindicating the presence of the analyte 28.

In an alternate embodiment for detecting anionic analytes, depicted inFIG. 15, Mode B, the ionophore of the sensor selectively binds ananionic analyte 28 or a group of anionic analytes. In certain suchembodiments, the sensor comprises a chromoionophore 24 which does notabsorb photons 25 emitted from the quantum dot 26, upon excitation,e.g., by light such as UV or visible, when the ionic analyte 28 is notbound to the ionophore 22 of the sensor. In such a state, thewavelengths of the photons 25 emitted by the quantum dot 26 are outsideof the absorbance range, e.g., the maximum absorbance range, of thechromoionophore 24 in a deprotonated state and the fluorescence detectedoutside of the polymer matrix 20 is attenuated or absent (FIG. 14, ModeB, sensor on the left). As the target ion 28 increases in concentrationin the sample solution, the anionic analyte 28 is drawn into the polymermatrix 20 through the coating 28, binding with the ion-selectiveionophore 22. To maintain charge neutrality in the polymer matrix 20,protons 23 diffuse from the sample solution into the polymer matrix 20through the coating 28, protonating the chromoionophores 24 such thatthe absorbance properties are altered. The protonated chromoionophore 24has a shifted absorbance region such that the photons 25 of the quantumdot 26 are not absorbed by the chromoionophore 24 (FIG. 14, Mode B,sensor on the right). The sensor signal is attenuated or extinguishedindicating the presence of the analyte 28.

The following is a non-limiting, illustrative list of target ion (21 or28)/ionophore 22 pairings suitable for use in the sensors: potassium/Potassium lonophore III (i.e., BME-44,2-Dodecyl-2-methyl-1,3-propanediylbis[N-[5′-nitro(benzo-15-crown-5)-4′-yl]carbamate]), sodium/Sodiumlonophore IV (i.e., 2,3:11,12-Didecalino-16-crown-5 2,6,13,16,19Pentaoxapentacyclo [18.4.4.4^(7,12).0^(1,20).0^(7,12)] dotriacontane),sodium/Sodium Ionophore V (i.e.,4-Octadecanoyloxymethyl-N,N,N′,N′-tetracyclohexyl-1,2-phenylenedioxydiacetamide),sodium/Sodium Ionophore VI (i.e.,Bis[(12-crown-4)methyl]dodecylmethylmalonate Dodecylmethylmalonic acidbis[(12-crown-4)methyl ester]), sodium/Sodium Ionophore X(4-tert-Butylcalix[4]arene-tetraacetic acid tetraethylester),calcium/Calcium lonophore III (i.e., Calimycin), and calcium/Calciumionophore IV (i.e., N,N-Dicyclohexyl-N′,N′-dioctadecyl-diglycolicdiamide). For target anions, illustrative target ion/ionophore pairingsinclude chloride/Chloride Ionophore III (i.e.,3,6-Didodecyloxy-4,5-dimethyl-o-phenylene-bis(mercury chloride) andnitrite/Nitrite lonophore I (i.e., Cyanoaqua-cobyrinic acidheptakis(2-phenylethyl ester)).

In various embodiments, ion-detecting sensors may be constructed todirectly detect the presence of particular ions. As illustrated in thetables below, it is known in the art that certain diseases affectparticular ion channels in a cell. Accordingly, assays for those ionsutilizing the present invention may furnish a diagnostic tool todetermine the presence of particular diseases. Accordingly, the scope ofthe present invention should be understood to also include theapplication of the heretofore-described subject matter to measure theions set forth in the following tables, as well as their application todiagnose the presence of the associated diseases also appearing in thefollowing tables.

Channel- forming Channel Gene unit/ligand OMIM Disease Cation channels:CHRNA1/ACHRA CHRNA1 α, ACh 100690 Myasthenia congenita CHRNA4 CHRNA4 α,ACh 118504 Autosomal dominant nocturnal frontal lobe epilepsy CHRNB2CHRNB2 β, ACh 118507 Autosomal dominant nocturnal frontal lobe epilepsyPolycystin-2 PKD2 α 173910 Autosomal dominant polycystic kidney disease(ADPKD) CNGA3 CNGA3 α, cGMP 60053 Achromatopsia 2 (color blindness)CNGB1 CNGB1 β, cGMP 600724 Autosomal recessive retinitis pigmentosaCNGB3 CNGB3 β, cGMP 605080 Achromatopsia 3 Sodium channels: Na. 1.1SCN1A α 182389 Generalized epilepsy with febrile seizures (GEFS+) Na.1.2 SCN2A α 182390 Generalized epilepsy with febrile and afebrileseizures) Na. 1.4 SCN4A α 603967 Paramyotonia congenital, potassiumaggressive myotonia, hyperkalemic periodic paralysis Na. 1.5 SCN5a α600163 Long-QT syndrome, progressive familial heart block type 1,Brugada syndrome (idiopathic ventricular arrhythmia) SCNIB SCN1B β600235 Generalized epilepsy with febrile seizures (GEFS+) ENACα SCNNIA α600228 Pseudohypoaldosteronism type 1 (PHA1) ENaCβ SCNN1B β 600760 PHA1,Liddle syndrome (dominant hypertension ENaCγ SCNN1G γ 600761 PHA1,Liddle syndrome Potassium channels: K, 1.1. KCNA1 α 176260 Episodicataxia with myokymia KCNQI/K, LQT1 KCNQ1 α 192500 Autosomal dominantlong-QT syndrome (Romano-Ward) Autosomal recessive long-QT syndrome withdeafness (Jervell-Lange-Nielsen) KCNQ2 KCNQ2 α 602235 BFNC (epilepsy),also with myokymia KCNQ3 KCNQ3 α 602232 BFNC (epilepsy) KCNQ4 KCNQ4 α603537 DFNA2 (dominant hearing loss) HERG/KCNH2 KCNH2 α 152427 Long-QTsyndrome Kir1.1/ROMK KCNJ1 α 600359 Bartter syndrome (renal salt loss,hypokalemic alkalosis) Kir2.1/IRK/ KCNJ2 α 600681 Long-QT syndrome withdysmorphic KCNJ2 features (Andersen syndrome) Kir6.2/KATATP_(ATP) KCNJ11α 600937 Persistent hyperinsulinemic hypoglycemia of infancy (PHHI) SURISURI β 600509 PHHI KCNE1/Mink/ISK KCNE1 β 176261 Autosomal dominantlong-QT syndrome (Romano-Ward) Autosomal recessive long-QT syndrome withdeafness (Jervell-Lange-Nielson) KCNE2/MiRP1 KCNE2 β 603796 Long-QTsyndrome KCNE3/MiRP2 KCNE3 β 604433 Periodic paralysis Calcium channels:Ca. 1.1 CACNA1S α 114208 Hypokalemic periodic paralysis, malignanthyperthermia Ca, 1.4 CACNA1F α 300110 X-linked congenital stationarynight blindness Ca, 2.1 CACNA1A α 601011 Familial hemiplegic migraine,episodic staxia, spinocerebella ataxia type 6 RyRI RYR1 α 180901Malignant hyperthermia, central core disease RyR2 RYR2 α 180902Catecholaminergic polymorphic ventricular tachycardia, arrhythmogenicright ventricular dysplasia type 2 Chloride channels: CFTR ABCC7 α602421 Cystic fibrosis, congenital bilateral asplasia of vas deferenceCIC-1 CLCN1 α 118425 Autosomal recessive (Becker) or dominant (Thomsenmyotonia CIC-5 CLCN5 α 300008 Dent's disease (X-linked proteinuria andkidney stones) CIC-7 CLCN7 α 602727 Osteopetrosis (recessive ordominant) CIC-Kb CLCNKB α 602023 Bartter syndrome type III Barttin BSNDβ 606412 Bartter syndrome type IV (associated with sensorineuraldeafness) GLRA1 GLRA1 α, glycine 138491 Hyperekplexin (startle disease)GABAα1 GABRA1 α GABA 137160 Juvenile myoclonus epilepsy GABAγ2 GABRG2 γ,GABA 137164 Epilepsy Gap junction channels: Cx26 GJB2 121011 DFNB3(autosomal dominant hearing loss) DFNB1 (autosomal recessive hearingloss) Cx30 GJB4 605425 DFNA3 Cx31 GJB3 603324 DFNA2 Cx32 GJB1 304040CMTX(X-linked Charcot-Mari-Tooth neuropathy) AChR α7 Inflammation ClC7Osteoporosis Ether-a-go-go Cancer (eag, erg, elk) Gardos channel Sicklecell anemia P2X7 Immune disorders TRPC6 Asthma, COPD TRPM1 MelanomaTRPM2 Asthma TRPM4 Immune disorders TRPM7 Stroke TRPM8 Prostate cancerTRPV1 Urinary incontinence, pain The third column classifies channelproteins into α, β, and γ subunits, where α subunits are always directlyinvolved in pore formation, Several β subunits are only accessory (i.e..do not form pores), as is the case, for example, with SCN1B and barttin.Others (e.g. of ENaC and GABA receptors) participate in pore formation.For ligand-gated channels, the ligand is given. Note that GABA andglycine act from the extracellular side, whereas cGMP is anintracellular messenger.

Sodium Channel Gene Accession ID Gene Locus Type/Disease TissueExpression SCN1A GDB: 118870 2q24 SCN1, vg type 1, Brain S71446α-subunit (280 KDa) SCN1B GDB: 127281 19ql3.1 Hs.89634, vg type 1 Brain,heart, skeletal U12188-12104 β₁ subunit (38 KDa) muscle L16242, L10338SCN2A1 GDB: 120367 2q23 SCN2A, HBSC1, vg type II, Brain, peripheralnerve α₁ - subunit (280 KDa) SCN2A2 CDB: 133727 2q23-24.1 HBSCH, vg typeII, Brain α₂ - subunit vg type II, β₂ - subunit (33 KDa) SCN2B GDB:118871 AF019498 SCN3A GDB: 132151 2q24-31 vg type III, Brain S69887α-subunit (280 kDa) SCN4A GDB: 125181 17q23.1-25.3 SkM1, vg type IVSkeletal muscle L04216-L04236 α - subunit (260 kDa), hyperkalemicperiodic paralysis, paramyotonia congentia, potassturn- aggravatedmyotonia SCN4B GDB: 125182 3q21 vg type IV, β-subunit, Heart, fetalskeletal SCN5A GDB: 132152 SkM2, hH1, vg type V, muscle α-subunit, longQ-T syndrome 3 SCN6A GDB: 132153 2q21-23 Hs99945, vg type VI, Heart,uterus, fetal and α-subunit denervated skeletal muscle SCN7A GDB: 22813712q13 vg type VII, α-subunit Brain, spinal cord SCN8A GDB: 631695 vgtype VIII, α-subunit, motor end-plate disease + ataxia in mice SCN9AGDB: 3750013 vg type IX, α -subunit Thyroid and adrenal glandneuroendocrine type SCN10A GDB: 750014 lpter-p36.3 hPN3, vg type XSensory neurons, dorsal root ganglia SCNN1A GDB: 366596 12pt3 SCNN1, nvgtype 1 Kidney, lung, colon Z92978 α-subunit of ENaC SCNN1B GDB: 43447116p12.2-p12.1 nvg 1 β-subunit, Liddle's Kidney, lung, colon syndrome,pseudohypoaldosterontsm I SCNN1D GDB: 6053678 1p36.3-p36.2 DnaCh, nvg 1δ-subunit Kidney, lung, colon SCNN1G GDB: 568769 16p122-p12.1 nvg 1γ-subunit, Liddle's Kidney, lung, colon X87160 syndrome, U53835-53853pseudohypoaldosterontsm I Calcium Channel Gene Accession ID Gene LocusType/Disease Tissue Expression CACNA1A GDB: 126432 19p13 P/Q typeα_(1A)-subunit, Brain (cortex, bulbus, CACNL1A4 Z80114-Z80155, 19p13.1eqisodic ataxia 2, familial olfacorius, hippocampus, X99697, U79666hemiplegic migraine, cerebellum, brain stem), spinocerebellar ataxia 6;motoneurons, kidney tottering, leaner, and rolling mice CACNA1B GDB:580689 9q34 CACNN, N-type α_(1A)- Central, peripheral CACNL1A5 M94172,M94173 subunit nervous system CACNA1C GDB: 126094 12p13 CCHL1A1, L-typeα_(1A)- Heart, fibroblasts, lung, CACNL1A1 L29636, L29634, 12p13.3subunit smooth muscle (2 splice L29629 variants) CACNA1D GDB: 1288723p14.3 CCHL1A2, L-type α_(1D)- Brain, pancreas, CACNL1A2 3p21.3.2?subunit neuroendocrine CACNA1E GDB: 434408 1q25-31 R-type α_(1C)-subunitBrain, skeletal muscle CACNL1A6 (end plate) CACNA1F GDB: 6053864Xp11.23-11.22 α_(1F)-Subunit Retina CACN1AG AF27964 17q22 T-typea_(1G)-subunit Brain CACNA1S GDB: 126431 1q31-32 L-type α_(1B)-subunitSkeletal muscle (brain, CACNL1A8 Z22672, L33798 (5% 212, 95% 190 kDa),kidney) U30666-U30707 malignant hyperthermia 5, hypokalemic periodicparalysis CACNA2 GDB: 132010 7q21-22 CACNA2, CACNA2D1, α_(2A); skeletalmuscle, CACNL2A Z28613, Z28609 α_(g 8)-subunit (175 kDa), heart, brain,ileum; α_(2B); Z28605, Z28602 MHS3 brain; α_(2CVD) aorta Z28699, M76559CACNB1 GDB: 132012 17q21-22 β₁-Subunit β₁A/M; skeletal muscle CACNLB1GDB: 1073281 (524 aa, 54 kDa) β₁B/C; brain, heart, U86952-U86961 spleenM76560, L06111 GDB: 193328 CACNB2 GDB: 132014 10p12 MYSB, β₂-subunitβ₂-A/B/E; brain, heart, CACNLB2 Q08289 lung, aorta CACNB3 GDB: 34102312q13 β₂-subunit (482 aa) Brain, heart, lung, CACNLB3 L27584 spleen,skeletal and smooth muscle, aorta, trachea, ovary, colon CACNB4 GDB:6028693 2q22-23 β₂-subunit, lethargic mice Brain, kidney CACNG GDB:132015 17q24 γ-Subunit Skeletal muscle, lung CACNLG L07738 (222 aa, 30kDa) CACNG2 γ2-Subunit, stargazin, Brain absence epilepsy stargazer,waggler mice RYR1 GDB: 120359 19q13.1 Ryanodine receptor 1, Ca Skeletalmuscle, testis, release channel, 3 splice brain, submaxillary andvariants, malignant adrenal glands, spleen hyperthermia 1, central coredisease RYR2 GDB: 125278 1pter-qter RYR2, calcium release Heart, smoothmuscle lq42.1-43 channel RYR3 GDB: 138451 15q14 RYR3, calcium releaseBrain, neonatal skeletal 15q14-15 channel muscle, adult diaphragmPotassium Channel Gene Accession ID Gene Locus Type/Disease TissueExpression KCNA1 GDB: 127903 12p13 RBK1, HUK1, MBK1, AEMK, Brain, nerve,heart, LO2750 Kv1.1, Shaker homolog 1, skeletal muscle, retina, Shaker,episodic ataxia 1 pancreatic islet (with myokymia) KCNA1B 3q26.1 Kvβ1.1,Kvβ1.3 (splice product), β-subunit KCNA2 GDB: 128062 12pter-qter HK4,Kv1.2, Shaker Brain, nerve, heart, X17622 homolog 2 pancreatic isletKCNA2B 1p36.3 Kvβ1.2, β-subunit KCNA8 GDB: 128079 1p13.3 Hs.1750, MK3,HLK3, Skeletal muscle, L23499 HPCN3, Kv1.3, Shaker lymphocytes (brain,lung, homolog 3 thymus, spleen) KCNA4 GDB: 126730 11p14 Hs.89647,Hs.1854, HK1, Brain, nerve, heart, fetal M60450 HPCN2, Kv1.4, Shakerskeletal muscle, M55514 homolog 4 pancreatic islet KCNA4L GDB: 38605911q14 Shaker homolog type 4- like KCNA5 GDB: 127904 12p13.3-13.2Hs.89509, HK2, HPCNI, Brain, heart, kidney, M83254 12p13 Kv1.5 Shakerhomolog 5 lung, skeletal muscle, M60451 12p13.33-12.31 pancreatic isletKCNA6 GDB: 128080 12p13 HBK2, Kv1.6, Shaker Brain, pancreatic isletX17622 homolog 6 KCNA7 GDB: 127905 19q13.3 HAK6, Kv1.7 Shaker homolog 7KCNA8 see KCNQ1 KCNA9 see KCNQ1 KCNA10 GDB: 5885822 Shaker homolog type10, cGMP activated KCNB1 GDB: 128081 20q13.2 Kv2.1, Shab homolog 1Brain, heart, kidney, retina, skeletal muscle KCNB2 Kv2.2, Shab homolog2 Brain, heart, retina KCNC1 GDB: 128082 11p15.1 Kv3.1, Shaw homolog 1Brain, skeletal muscle, S56770 spleen, lymphocytes M96747 KCNC2 GDB:127906 19q13.3-13.4 Kv3.2, Shaw homolog 2 Brain KCNC3 GDB: 12790719q13.3 Kv3.3, Shaw homolog 3 Brain, liver KCNC4 GDB: 127908 1p21 Kv3.4,HKSHIIIC, Shaw Brain, skeletal muscle homolog 4 KCND1 GDB: 128083 Kv4.1,Shal homolog 1 Brain KCND2 GDB: 134771 RK5, Kv4.2, Shal Brain, heart,aorta homolog 2 KCND3 GDB: 134772 Kv4.3, KSHIVB, Shal homolog 3 KCNE1GDB: 127909 21q22.1-22.2 MinK, ISK, vg Isk Kidney, submandibular homolog1 (129 aa), long gland, uterus, heart, Q-T syndrome 5 cochlea, retinaKCNMA1 GDB: 386031 10pter-qter SLO, Hs.62679, α-subunit Fetal skeletalmuscle U09383-4 7q32.1 member 1, α-subunit of U02632 maxiK or BK channelKCNMB1 GDB: 6099615 5q34 hSLO-β, β-subunit member 1 Smooth, fetalskeletal U42600 (191 aa), β-subunit of muscle, brain (hippocampus, maxIK or BK channel corpus callosum) KCNN1 U69883 SK(Ca)1,small-conductance Brain, heart Ca-activated K channel,apamin-insensitive KCNN2 SK(Ca)2, apamin sensitive Brain, adrenal glandKCNN3 Y08263 1q? SK(Ca)3, small-conductance Brain, heart, (humanAA285078 Ca- activated K channel, embryonic) skeletal intermediatemuscle, liver apamin sensitivity KCNN4 AF022150 19q13.2 IK1,intermediate- T lymphocytes, colon, AF022797 conductance Ca-activatedsmooth muscles, prostata, AF033021 K channel, KCa4, SK4, red bloodcells, neurons AF000972 Gantos channel KCNQ1 GDB: 741244 11p15.5 KCNA9,(KV)LQT1, Heart, cochlea, kidney, U40990 KQT-like subfamily lung,placenta, colon member 1, long Q-T syndrome 1 KCNQ2 GDB: 9787229,20q13.3 KQT-like subfamily Brain Y15065, AF033348 member 2 (872 aa)KCNQ3 GDB: 9787230 8q24.22-24.3 KQT-like subfamily Brain AF033347 member3 (825 aa) HERG GDB: 407638 7q35-36 HERG, similar to ether-a- Brain,heart go go (eag), Ikr, long Q-T syndrome 2 KCNJ1 GDB: 204206 11q24ROMK1, Kirl.1, Hs.463, Kidney, pancreatic islets U65406, U12541Bartter/hyperprostaglandin E syndrome KCNJ2 GDB: 278964 17pter-qterIRK1, Kir2.1, Hs.1547 Muscle, neural tissue, U12507 heart KCNJ3 GDB:278325 2q24.1 GIRK1, Kir3.l Heart, cerebellum U50964 KCNJ4 GDB: 37408022q13.1 HIR, HIRK1, HIRK2, Kir2.3 Heart, skeletal muscle, Z97056 brainKCNJ5 GDB: 547948 11q24 CIR. KATP1, GIRK4, Kir3.4 Heart, pancreas KCNJ6GDB: 547949 21q22.1 KCNJ7, GIRK2, KATP2, BIR1, Cerebellum, pancreaticU24660 Kir3.2, ataxia, weaver mice islet KCNJ8 GDB: 633096 12p11.23]Kir6.1, uKATP, ubiquitous Brain, heart, skeletal, K_(ATP) α-subunitsmooth muscle, others KCNJ10 GDB: 3750203 1q22-23] Kir1.2, Kir4.1 GliaKCNJ11 GDB: 7009893 [11p15.1] Kir6.2, BIR, K(ATP) Pancreatic isletsα-subunit, hyperinsulinemic hypoglycemia KCNJ12 GDB: 4583927 [17p11.1]Kir2.2 KCNJ15 GDB: 6275865 [21q22.2] Kir4.2 KCNJN1 GDB: 6108062 [ ]Kir2.2v, subfamily inhibitor 1 SUR1 GDB: 591970 [11p15.1] SUR(1),sulfonylurea Pancreatic islets receptor, K(ATP) β-subunit,hyperinsulinemic hypoglycemia SUR2 12p12.1] SUR2, SUR2A, B, 2A: heart,2B: brain, sulfonylurea receptor 2 liver, skeletal, smooth (1545-aa),β-subunit of muscle, urinary bladder K(ATP) KCNK1 GDB: 6045446 1q42-43DPK, TWIK1 Kidney KCNK2 1q41 TREK1 Brain KCNK3 GDB: 9773281 2p23 TASKKidney

Therapeutic Target Enzyme Family Assay Alzheimer's CMGC ERK2 (P42mapk)Alzheimer's Phospholipase PLA2 Alzheimer's Cyclooxygenases COX2Alzheimer's CaMK MARKI Alzheimer's CaMK MARK2 Alzheimer's AGC PKCalphaAlzheimer's AGC PKCgamma Alzheimer's AGC PKCgamma Alzheimer's Cysteineproteases caspase-3 Alzheimer's Cysteine proteases caspase-6 Alzheimer'sAspartic proteases BACE-1 (beta- secretase) Alzheimer's Asparticproteases cathepsin D Alzheimer's Aspartic proteases cathepsin EAlzheimer's Metalloproteases ACE Alzheimer's Metalloproteases ACEAlzheimer's Metalloproteases TACE Alzheimer's NO synthases constitutiveNOS (cerebellar) Alzheimer's Monoamine &neurotransmitteracetylcholinesterase synthesis & metabolism Alzheimer's Monoamine&neurotransmitter COMT (catechol-O- synthesis & metabolism methyltransferase) Alzheimer's Monoamine &neurotransmitter MAO-A synthesis &metabolism Alzheimer's Monoamine &neurotransmitter MAO-B synthesis &metabolism Alzheimer's Monoamine &neurotransmitter tyrosine hydroxylasesynthesis & metabolism Alzheimer's Phospholipase C PLC Alzheimer'sMiscellaneous enzymes xanthine oxidase/ superoxide 02 - scavengingDependence/Addiction AGC PKA Dependence/Addiction AGC PKCalphaDependence/Addiction AGC PKCbeta 1 Dependence/Addiction AGC PKCbeta 2Dependence/Addiction AGC PKCdelta Dependence/Addiction Monoamine&neurotransmitter GABA transaminase synthesis & metabolismDependence/Addiction Cyclases adenylyl cyclase (stimulated)Dependence/Addiction Phospholipase C PLC Dependence/Addiction ATPaseATPase (Na⁺/K⁺) Inflammation/Arthritis/Allergy RTK EGFR kinaseInflammation/Arthritis/Allergy RTK FLT-1 kinase (VEGFR1)Inflammation/Arthritis/Allergy RTK KDR kinase (VEGFR2)Inflammation/Arthritis/Allergy CTK Fyn kinaseInflammation/Arthritis/Allergy CTK HCK Inflammation/Arthritis/AllergyCTK Lek kinase Inflammation/Arthritis/Allergy CTK Lyn kinaseInflammation/Arthritis/Allergy CTK ZAP70 kinaseInflammation/Arthritis/Allergy CMGC ERK2 (P42mapk)Inflammation/Arthritis/Allergy CMGC JNK 1 Inflammation/Arthritis/AllergyCMGC JNK 2 Inflammation/Arthritis/Allergy CMGC P38alpha kinaseInflammation/Arthritis/Allergy Phospholipase PLA2Inflammation/Arthritis/Allergy Cyclooxygenases COX1Inflammation/Arthritis/Allergy Cyclooxygenases COX2Inflammation/Arthritis/Allergy TXA2 synthetase TXA2 synthetaseInflammation/Arthritis/Allergy CaMK MAPKAPK2Inflammation/Arthritis/Allergy AGC PKA Inflammation/Arthritis/AllergyLipoxygenases 12-lipoxygenase Inflammation/Arthritis/AllergyLipoxygenases 15-lipoxygenase Inflammation/Arthritis/Allergy Serineproteases elastase Inflammation/Arthritis/Allergy Serine proteasescathepsin G Inflammation/Arthritis/Allergy Serine proteases kallikreinInflammation/Arthritis/Allergy Serine proteases tryptaseInflammation/Arthritis/Allergy Cysteine proteases caspase-1Inflammation/Arthritis/Allergy Cysteine proteases caspase-4Inflammation/Arthritis/Allergy Cysteine proteases caspase-5Inflammation/Arthritis/Allergy Cysteine proteases cathepsin BInflammation/Arthritis/Allergy Cysteine proteases cathepsin XInflammation/Arthritis/Allergy Aspartic proteases cathepsin EInflammation/Arthritis/Allergy Metalloproteases MMP-1Inflammation/Arthritis/Allergy Metalloproteases MMP-2Inflammation/Arthritis/Allergy Metalloproteases MMP-3Inflammation/Arthritis/Allergy Metalloproteases MMP-7Inflammation/Arthritis/Allergy Metalloproteases MMP-8Inflammation/Arthritis/Allergy Metalloproteases MMP-9Inflammation/Arthritis/Allergy Metalloproteases MMP-13Inflammation/Arthritis/Allergy Metalloproteases MT1-MMP (MMP-14)Inflammation/Arthritis/Allergy Metalloproteases TACEInflammation/Arthritis/Allergy Phosphatases phosphatase CD45Inflammation/Arthritis/Allergy Phosphodiesterases PDE2Inflammation/Arthritis/Allergy Phosphodiesterases PDE4Inflammation/Arthritis/Allergy Phosphodiesterases acid sphingomyelinaseInflammation/Arthritis/Allergy Monoamine & neurotransmitter HNMT(histamine N- synthesis & metabolism methyltransferase)Inflammation/Arthritis/Allergy Miscellaneous enzymes myeloperoxidaseInflammation/Arthritis/Allergy Miscellaneous enzymes xanthine oxidase/superoxide 02 - scavenging Neuroprotection RTK TRKB Neuroprotection CMGCCDK5 Neuroprotection CMGC DYRKla Neuroprotection CMGC ERK1Neuroprotection CMGC ERK2 (P42mapk) Neuroprotection MCGC JCK 3Inflammation/Arthritis/Allergy Metalloproteases MMP-13Inflammation/Arthritis/Allergy Metalloproteases MT1-MMP (MMP-14)Inflammation/Arthritis/Allergy Metalloproteases TACEInflammation/Arthritis/Allergy Phosphatases phosphatase CD45Inflammation/Arthritis/Allergy Phosphodiesterases PDE2Inflammation/Arthritis/Allergy Phosphodiesterases PDE4Inflammation/Arthritis/Allergy Phosphodiesterases acid sphingomyelinaseInflammation/Arthritis/Allergy Monoamine & neurotransmitter HNMT(histamine N- synthesis & metabolism methyltransferase)Inflammation/Arthritis/Allergy Miscellaneous enzymes myeloperoxidaseInflammation/Arthritis/Allergy Miscellaneous enzymes xanthine oxidase/superoxide 02 - scavenging Neuroprotection RTK TRKB Neuroprotection CMGCCDK5 Neuroprotection CMGC DYRKla Neuroprotection CMGC ERK1Neuroprotection CMGC ERK2 (P42mapk) Neuroprotection MCGC JCK 3Neuroprotection Cyclooxygenases COXI Neuroprotection CyclooxygenasesCOX2 Neuroprotection CaMK CaMK2alpha Neuroprotection AGC PKANeuroprotection Cysteine proteases caspase-3 NeuroprotectionPhosphodiesterases PDEI Neuroprotection Phosphodiesterases PDE6Neuroprotection NO synthases constitutive NOS (endothelial)Neuroprotection NO synthases constitutive NOS (cerebellar)Neuroprotection Monoamine & neurotransmitter acetylcholinesterasesyntheses & metabolism Neuroprotection Monoamine & neurotransmitter COMT(catechol-O- syntheses & metabolism methyl transferase) NeuroprotectionMonoamine & neurotransmitter GABA transaminase syntheses & metabolismNeuroprotection Monoamine & neurotransmitter HNMT (histamine N-syntheses & metabolism methyltransferase) Neuroprotection Monoamine &neurotransmitter MAO-A syntheses & metabolism Neuroprotection Monoamine& neurotransmitter MAO-A syntheses & metabolism NeuroprotectionMonoamine & neurotransmitter PNMT syntheses & metabolism(phenylethanoiamine- N-methyl transferase) Neuroprotection Monoamine &neurotransmitter tyrosine hydroxylase syntheses & metabolismNeuroprotection Cyclases guanylyl cyclase (basal) NeuroprotectionCyclases guanylyl cyclase (stimulated) Neuroprotection ATPase ATPase(Na+/K+) Neuroprotection Miscellaneous enzymes xanthineoxidase/superoxide 02 - scavenging Parkinson CMGC JNK 1 ParkinsonPhospholipase PLA2 Parkinson Cyclooxygenases COX2 Parkinson Cysteineproteases caspase-3 Parkinson NO synthases constitutive NOS (cerebellar)Parkinson Monoamine & neurotransmitter acetylcholinesterase syntheses &metabolism Parkinson Monoamine & neurotransmitter COMT (catechol-O-syntheses & metabolism methyl transferase Parkinson Monoamine &neurotransmitter MAO-A syntheses & metabolism Parkinson Monoamine &neurotransmitter MAO-B syntheses & metabolism Cancer RTK Axl kinaseCancer RTK c-kit kinase Cancer RTK c-kit kinase Cancer RTK EGFR kinaseCancer RTK EphA1 kinase Cancer RTK EphA3 kinase Cancer RTK EphA4 kinaseCancer RTK EphB2 kinase Cancer RTK FGFR1 kinase Cancer RTK FGFR2 kinaseCancer RTK FGFR3 kinase Cancer RTK FGFR4 kinase Cancer RTK FLT-1 kinase(VEGFR1) Cancer RTK FLT-3 kinase Cancer RTK FLT-4 kinase (VEGFR3) CancerRTK Fms/CSFR kinase Cancer RTK HER2/ErbB2 kinase Cancer RTK HER4/ErbB4kinase Cancer RTK KDR kinase (VEGFR2) Cancer RTK PDGFRalpha kinaseCancer RTK PDGFRbeta kinase Cancer RTK Ret kinase Cancer RTK TIE2 kinaseCancer RTK TRKA Cancer CTK Abl kinase Cancer CTK BLK Cancer CTK BMX (Bk)kinase Cancer CTK BRK Cancer CTK BTK Cancer CTK CSK Cancer CTK FAKCancer CTK Fes kinase Cancer CTK Fyn kinase Cancer CTK JAK2 Cancer CTKJAK3 Cancer CTK Lck kinase Cancer CTK PYK2 Cancer CTK Src kinase CancerCTK Syk Cancer CTK Yes kinase Cancer CMGC CDC2/CDK1 (cycB) Cancer CMGCCDK2 (cycE) Cancer CMGC CDK4 (cycD1) Cancer CMGC CDK5 Cancer CMGC CK2(casein kinase 2) Cancer CMGC DYRKla Cancer CMGC ERK1 Cancer CMGC ERK2(P42mapk) Cancer CMGC HIPK2 Cancer CMGC IKKalpha Cancer CMGC IKKbetaCancer CMGC JNK 1 Cancer CMGC JNK 2 Cancer CMGC NEK1 Cancer CMGC NEK2Cancer CMGC NEK4 Cancer CMGC p38alpha kinase Cancer CMGC p38beta 2kinase (SAPK2b2) Cancer CMGC p38delta kinase Cancer CMGC p38ganunakinase Cancer Cyclooxygenases COX2 Cancer CaMK CaMK1delta Cancer CaMKCaMK Cancer CaMK CHK1 Cancer CaMK CHK2 Cancer CaMK DAPK1 Cancer CaMKDAPK2 Cancer CaMK MAPKAPK2 Cancer CaMK MAPKAPK3 Cancer CaMK MAPKAPK5(PRAKO Cancer CaMK MAARK1 Cancer CaMK MARK2 Cancer CaMK MARK4 CancerCaMK Pim 1 kinase Cancer CaMK Pirn2 kinase Cancer AGC Akt1/PKBalphaCancer AGC Akt2/PKBbeta Cancer AGC Akt3/PKBgamma Cancer AGC AurA/Aur2kinase Cancer AGC AurB/Aur1 kinase Cancer AGC AurC/Aur3 kinase CancerAGC P70S6Ke Cancer AGC PDK1 Cancer AGC PKA Cancer AGC PKCalpha CancerAGC PKCbeta 1 Cancer AGC PKCbeta 2 Cancer AGC PKCdelta Cancer AGCPKCgamma Cancer AGC PKG2 Cancer AGC ROCK1 Cancer AGC ROCK2 Cancer AGCRSK2 Cancer. AGC SGKI Cancer Lipoxygenases 12-lipoxygenase Cancer TKLRAF-1 kinase Cancer STE MEK1/MAP2KI Cancer STE MKK4/JNK1 Cancer STE MKK6Cancer STE PAK1 Cancer STE PAK2 Cancer Serine proteases elastase CancerSerine proteases cathepsin G Cancer Cysteine proteases caspase-2 CancerCysteine proteases caspase-3 Cancer Cysteine proteases caspase-8 CancerCysteine proteases caspase-9 Cancer Cysteine proteases cathepin B CancerCysteine proteases cathepsin H Cancer Cysteine proteases cathepsin LCancer Cysteine proteases cathepsin X Cancer Aspartic proteasescathepsin D Cancer Aspartic proteases cathepsin E CancerMetalloproteases MMP-1 Cancer Metalloproteases MMP-2 CancerMetalloproteases MMP-3 Cancer Metalloproteases MMP-7 CancerMetalloproteases MMP-8 Cancer Metalloproteases MMP-9 CancerMetalloproteases MMP-12 Cancer Metalloproteases MMP-13 CancerMetalloproteases MT1-MMP (MMP-14) Cancer Metalloproteases TACE Cancer'Metalloproteases MMP-1 Cancer Phosphatases phosphatase 1B CancerPhosphatases phosphatase 2B Cancer Phosphodiesterases PDE2 CancerPhosphodiesterases PDE4 Cancer Phosphodiesterases PDES CancerPhosphodiesterases acid spingomyelinase Cancer NO synthases constitutiveNOS (endothelial) Cancer NO synthases constitutive NOS (cerebellar)Cancer Cyclases adenylyl cyclase (basal) Cancer Cyclases adenylylcyclase (stimulated) Cancer Phospholipase C PLC Cancer Miscellaneousenzymes myeloperoxidase Cancer Miscellaneous enzymes xanthineoxidase/superoxide 02- scavenging Diabetes RTK Ax1 kinase Diabetes RTKEGFR kinase Diabetes RTK IGFIR kinase Diabetes CMGC ERK2 (P42mapk)Diabetes CMGC Jnk1 Diabetes Cyclooxygenases COX2 Diabetes TXA2synthetase TXA2 synthetase Diabetes CaMK AMPKalpha Diabetes AGCAkt1/PKBalpha Diabetes AGC Akt2/PKBbeta Diabetes AGC Akt3/PKBgammaDiabetes AGC PDK1 Diabetes AGC PKA Diabetes AGC PKCalpha Diabetes AGCPKCbeta I Diabetes AGC PKCbeta 2 Diabetes AGC PKCgamma Diabetes AGC SGK2Diabetes Metalloproteases ACE Diabetes Metalloproteases MMP-1 DiabetesMetalloproteases MMP-2 Diabetes Metalloproteases MMP-3 DiabetesMetalloproteases MMP-7 Diabetes Metalloproteases MMP-8 DiabetesMetalloproteases MMP-9 Diabetes Metalloproteases MT1-MMP (MMP-14)Diabetes Metalloproteases TACE Diabetes Phosphodiesterases PDE3 DiabetesPhosphodiesterases PDE4 Diabetes Phosphodiesterases PDE5 Diabetes NOsynthases constitutive NOS (endothelial) Diabetes Monoamine &neurotransmitter acetylcholinesterase synthesis & metabolism DiabetesMonoamine & neurotransmitter GABA transaminase synthesis & metabolismDiabetes Monoamine & neurotransmitter MAO-B synthesis & metabolismDiabetes Cyclases adenylyl cyclase (basal) Diabetes Miscellaneousenzymes acetylCoA synthetase Diabetes Miscellaneous enzymes HMG-CoAreductase Diabetes Miscellaneous enzymes xanthine oxidase/superoxide 02-scavenging Metabolic Diseases Cyclooxygenases COX2 Metabolic DiseasesAGC PICA Metabolic Diseases Metalloproteases ACE Metabolic DiseasesPhosphodiesterases PDE3 Metabolic Diseases Phosphodiesterases PDE4Metabolic Diseases NO synthases constitutive NOS (endothelial) MetabolicDiseases Miscellaneous enzymes acetylCoA synthetase Metabolic DiseasesMiscellaneous enzymes HMG-CoA reductase Metabolic Diseases Miscellaneousenzymes xanthine oxidase/superoxide 02- scavenging Obesity CTK PYK2Obesity CMGC JNK1 Obesity CaMK AMPJakoga Obesity AGC PKA ObesityMetalloproteases ACE Obesity Metalloproteases ACE Obesity Phosphatasesphosphatase IB Obesity Phosphodiesterases PDE2 ObesityPhosphodiesterases PDE3 Obesity Monoamine & neurotransmitteracetylcholinesterase synthesis & metabolism Obesity ATPase ATPase(Na+/K+) Obesity Miscellaneous enzymes HMG-CoA reductase ReproductionPhospholipase PLA2 Reproduction Cyclooxygenases COX1 ReproductionCyclooxygenases COX2 Reproduction Phosphodiesterases PDE5 ReproductionNO synthases constitutive NOS (endothelial) Reproduction Cyclasesguanylyl cyclase (stimulated) Cystic Fibrosis Phospholipase PLA2 CysticFibrosis TXA2 synthetase TXA2 synthetase Cystic Fibrosis AGC PKA CysticFibrosis AGC PKCbeta 1 Cystic Fibrosis AGC PKCbeta 2 Cystic FibrosisSerine proteases elastase Cystic Fibrosis Serine proteases cathepsin GCystic Fibrosis Metalloproteases MMP-2 Cystic FibrosisPhosphodiesterases PDE3 Cystic Fibrosis Phosphodiesterases PDE5 CysticFibrosis Cyclases adenylyl cyclase (stimulated) Cystic FibrosisPhospholipase C PLC Cystic Fibrosis Miscellaneous enzymesmyeloperoxidase Immunosuppression Profile RTK EGFR kinaseImmunosuppression Profile CTK JAK3 Immunosuppression Profile CMGC ERK2(P42mapk) Immunosuppression Profile Cyclooxygenases COX1Immunosuppression Profile Cyclooxygenases COX2 Immunosuppression ProfileSerine proteases elastase Immunosuppression Profile Serine proteasescathepsin G Immunosuppression Profile Serine proteases tryptaseImmunosuppression Profile Cysteine proteases cathepsin BImmunosuppression Profile Metalloproteases ECE-1 ImmunosuppressionProfile Metalloproteases ECE-1 Immunosuppression ProfileMetalloproteases MMP-1 Immunosuppression Profile Metalloproteases MMP-2Immunosuppression Profile Metalloproteases MMP-9 ImmunosuppressionProfile Phosphatases phosphatase CD45 Immunosuppression ProfilePhosphodiesterases PDE4 Immunosuppression Profile Phosphodiesterasesacid spingomyelinase Immunosuppression Profile Cyclases adenylyl cyclase(basal) Immunosuppression Profile Cyclases adenylyl cyclase (stimulated)Migraine Cyclooxygenases COX2 Migraine NO synthases constitutive NOS(cerebellar) Migraine Monoamine & neurotransmitter GABA transaminasesynthesis & metabolism Migraine Cyclases guanylyl cyclase (stimulated)Pain CMGC ERK2 (42mapk) Pain Phospholipase PLA2 Pain CyclooxygenasesCOXI Pain Cyclooxygenases COX2 Pain AGC PICA Pain Serine proteaseselastase Pain Metalloproteases MMP-1 Pain Metalloproteases MMP-2Immunosuppression Profile Serine proteases elastase ImmunosuppressionProfile Serine proteases cathepsin G Immunosuppression Profile Serineproteases tryptase Immunosuppression Profile Cysteine proteasescathepsin B Immunosuppression Profile Metalloproteases ECE-1Immunosuppression Profile Metalloproteases ECE-1 ImmunosuppressionProfile Metalloproteases MMP-1 Immunosuppression ProfileMetalloproteases MMP-2 Immunosuppression Profile Metalloproteases MMP-9Immunosuppression Profile Phosphatases Phosphatase CD45Immunosuppression Profile Phosphodiesterases PDE4 ImmunosuppressionProfile Phosphodiesterases acid spingomyelinase ImmunosuppressionProfile Cyclases adenylyl cyclase (basal) Immunosuppression ProfileCyclases adenylyl cyclase (stimulated) Migraine Cyclooxygenases COX2Migraine NO synthases constitutive NOS (cerebellar) Migraine Monoamine &neurotransmitter GABA transaminase synthesis & metabolism MigraineCyclases guanylyl cyclase (stimulated) Pain CMGC ERK2 (42mapk) PainPhospholipase PLA2 Pain Cyclooxygenases COXI Pain Cyclooxygenases COX2Pain AGC PICA Pain Serine proteases elastase Pain Metalloproteases MMP-1Pain Metalloproteases MMP-2 Pain Metalloproteases MMP-3 PainMetalloproteases MMP-7 Pain Phosphodiesterases PDE4 Pain NO synthasesconstitutive NOS (endothelial) Pain NO synthases constitutive NOS(cerebellar) Pain Monoamine & neurotransmitter GABA transaminasesynthesis & metabolism Pain Monoamine & neurotransmitter MAO-A synthesis& metabolism Pain Monoamine & neurotransmitter MAO-B synthesis &metabolism Pain Monoamine & neurotransmitter tyrosine hydroxylasesynthesis & metabolism Pain Miscellaneous enzymes xanthineoxidase/superoxide 02- scavenging

Sensor materials (including ion-detecting sensors and glucose-detectingsensors) as discussed herein can be sized and shaped in any suitableconfiguration that can be achieved using the polymer. For example, incertain embodiments, the nanosensors are non-spherical, such as a diskor a cube, or even sculpted or molded into a utilitarian or aestheticshape. A sensor emulsion can be spun, sprayed, or evaporated onto anysurface to create a porous sensor membrane. In certain embodiments, thesensor film can be of a size suitable for the application, such as thecoating of a glass slide, the bottoms of wells of a 96-well plate, oreven a beverage dispenser, such as a pitcher, tank, or bottle. Filmsformed from microspheres tend to expose a greater surface area of sensorto a given sample, yielding improved performance characteristics.

The film of the sensor can be produced in various ways. In oneimplementation, as described above, a predetermined amount of the sensormixture (e.g., the combined polymer phase, ionophore, quantum dots/dye,additive, and chromoionophore) is dissolved in a solvent, such as THF.The solution is then deposited, sprayed, or spun onto a surface. Thesolvent evaporates, leaving the sensor film on the surface.

In another implementation, the film is formed from a deposition ofsensor microspheres. To produce the microspheres, a sensor emulsion isformed by injecting a sensor suspension dissolved in THF (e.g., 16 mLTHF/100 mg PVC) into a pH buffered solution. The sensor suspensionincludes approximately 60 mg of DOS, 30 mg of PVC, and up toapproximately 5 mg of chromoionophore, additive, and ionophore. Theemulsion is then submerged in a sonicating water bath. Typically, 50 μLof the sensor suspension/THF solution is injected into 1,000-1,500 μL ofbuffered solution. The resulting emulsion contains a mixture ofspherical sensor particles ranging in size from 200 nm to 20 pm indiameter. In certain embodiments, the nanosensors range in size fromabout 5 nm to about 300 nm in diameter, such as about 20 nm to about 200nm in diameter, e.g., about 100 nm. In certain embodiments, thenanosensors that comprise only one quantum dot range in size from about5 nm to about 50 nm in diameter, such as about 5 nm to about 25 nm indiameter, e.g., 20 nm. In certain embodiments wherein the particles arenon-spherical, the diameter is measured at the widest dimension of thenanosensor. Particles of larger dimension are, of course, readilyprepared.

In certain aspects, a film of the sensor material or particles isdeposited on the surface of a support. In certain embodiments, thesupport is an instrument that can be placed in a solution such as aglass rod, a stirring bar, a straw, or glass beads. In certainembodiments, the support is a container in which the sample solution tobe evaluated can be contained. In certain embodiments, the surface ofthe support is partially coated with the sensor particles while in otherembodiments, the support surface is entirely coated with the sensorparticles. In certain embodiments, the sensors are incorporated withinthe support and the support is sculpted into a desired shape such as astir bar, a film, or a bead.

In certain embodiments, iCVD or piCVD may be used to coat sensors orsensor particles with a polymer or copolymer coating. In certainembodiments, the polymer or copolymer coatings may comprisebiocompatible polymer.

In certain embodiments, the invention includes methods for detecting thepresence of an analyte in a medium, comprising contacting a sensorparticle of the invention with a medium, exposing the quantum dot tolight energy that causes the quantum dot to emit photons and using adetector to detect the photons and determining the presence or absenceof analyte based on the detected photons. In certain embodiments, theanalyte is an ion, while in other embodiments, the analyte is achelatable analyte, such as glucose. In certain embodiments, the lightenergy is selected from ultraviolet, infrared, near infrared or visibleradiation. In certain embodiments, the light energy is ultraviolet. Incertain embodiments, the medium comprises water, blood, plasma, urine,or cytoplasm. In certain embodiments, the method of detecting analyte,e.g. ions or glucose, with a sensor particle of the invention isperformed in vitro.

In certain embodiments, the sensors are placed in contact with cells inbiological samples such as tissues outside of the host specimen. Incertain embodiments, the sensors are introduced to cells within a hostspecimen such as a plant or animal. The nanosensor particles may beintroduced into the cells in any suitable manner. In one method, theparticles are introduced into a buffer liquid deposited in thebiological sample holder. A voltage source then generates a voltagesufficiently strong to electroporate the cells, thereby allowing thenanosensor particles to enter directly into the cells. In anotherapproach, the surfaces of the nanosensor particles are first coated witha substance such as a surface modifier, a targeting moiety, aninternalizing moiety or any combination thereof, which assist theparticles in crossing through lipophilic membranes. The nanosensorparticles contact the cells which bring the particles into theirinterior in vesicles via endocytosis, pinocytosis, phagocytosis, orsimilar biological processes. In certain embodiments, the internalizingmoiety of the nanosensor particle breaks down the vesicle membrane,releasing the nanosensor particle into the cell cytoplasm. In stillother approaches, the particles may be introduced into cells using aglass needle or through ballistic bombardment.

To determine compartmentalization of nanosensors within the cells TEMand fluorescence staining can be used. TEM can be used to determinelocation of the nanosensor in a cell, to provide a good understanding ofnanosensor transport in the cell and serve as a validation of theco-localization staining. The second method, co-localization staining,can be used to determine endosomal release.

Dyes suitable for performing co-localization studies include: FM1-43,FM4-64, Fluorescein, Transferrin, and Lysotracker Red. FM1-43 is alipophilic dye that readily stains cell membranes. Previous studies haveshown the effectiveness of FM1-43 to stain endosomes. Its fluorescenceemission is typically greatly increased upon incorporation into ahydrophobic environment. FM1-43 will typically stain the plasma membraneof a cell and remain associated with the lipid bilayer as it forms anendosome. Dye that is not taken into the cell and remains on the plasmamembrane can be easily removed by gentle washing. FM4-64 is an analog ofFM 1-43 and behaves in a very similar fashion. It is more hydrophobicthen FM1-43 and therefore may be more suitable for endocytosis studies.FM4-64 has been well characterized as an endosomal stain. The longwavelength emission of FM4-64 may be advantageous when using sensors ofdifferent spectral properties similar to the other fluorescent stainsbeing utilized.

In some embodiments, the sensor is attached to the exterior of a cellrather than introduced into the interior. If, for example, the activityof an ion channel is to be studied, an ion-detecting sensor may beattached to the cell surface or placed in close proximity to the cellsurface in a location where ion concentrations are in flux, such asadjacent to an ion channel. The sensor may be positioned adjacent to theion channel of a cell, for example, by covalently linking one or moreantibodies that selectively bind the ion channel of interest to a sensorparticle as described above. The antibody-linked sensor particles may beadded to a cell suspension to bind to the ion channel. This approach canbe used to link sensors to any feature on the exterior of the cellmembrane to which antibodies selectively bind. Alternatively, thesensors may be attached to the cell membrane by other suitable couplingchemistries, e.g., biotin-(strept)avidin complexing or polysaccharidebinding. See the thesis “High Throughput Optical Sensor Arrays for DrugScreening” by Daniel I. Harjes (2006), available from the MassachusettsInstitute of Technology and incorporated herein by reference.

In certain embodiments, cells or tissues are contacted with bothnanosensor particles and a sensor film. In certain embodiments, thequantum dots used in the sensor film differ from the quantum dots usedin the nanosensor particles. In particular, the different quantum dotsdesirably have distinguishable fluorescence characteristics such that ananalysis module analyzing the output of a light sensor monitoring thesensor arrangement can differentiate between the output of the sensorfilm and the nanosensor particles. As a result, the analysis module candifferentiate between intracellular analyte concentration andextracellular analyte concentration. In an exemplary embodiment, thesensor film comprises quantum dots of a selected fluorescencewavelength, e.g., 560 nm, and the nanosensor particles comprise quantumdots of a selected fluorescence wavelength, e.g., 655 nm. In addition,an ion-detecting sensor film may include ionophores different from thoseincluded in ion-detecting sensor particles, e.g., nanosensor particlescomprising sodium ionophores and sensor films comprising potassiumionophores. Thus, the sensor arrangement can monitor the concentrationsof two different target ions.

In still another embodiment, the sensor film is coated onto the innersurface of a biological sample holder. And in another approach, toaccommodate multiwell plates, such as the 96-well plate format oftenused in assays, one embodiment of the present invention utilizes roundglass coverslips coated with the sensor film along with the cells to bemonitored. In certain embodiments, larger multiwell plates such as 384-and 1536-well plates are applied with a layer of sensor film disposed ona surface of some or all of the wells. In these embodiments, each wellcontains a single sensor type to track a specific species of interest;the various sensor types may differ in the ionophore employed andutilize quantum dots with fluorescence wavelengths that are the same orsimilar. The compound of interest is then added directly to the well.The multiwell plate is then placed in a fluorometer and the fluorescenceintensity is monitored with time.

In a typical implementation, a plurality of biological sample holdersholding biological samples is provided. Biological samples introducedinto the holders may include cells suspended in a buffer solution, butalternatively cells may be adhered to the walls of the biological sampleholders. Next, sensors are introduced into biological sample holdersand/or are introduced into the cells themselves. Alternatively, thesensors can coat the walls of the biological sample holders. Asdescribed above, nanosensor particles can be introduced either byelectroporating the cells via electrodes positioned in the biologicalsample holders or by the chemistry applied to the nanosensor particlesbreaching vesicle membranes within the cells. Similarly, the sensors canbe introduced into the cells using pico-injection, bead loading, a genegun, or through liposomal delivery techniques known in the art.

An agent, such as a therapeutic, toxin, biological macromolecule (suchas a nucleic acid, an antibody, a protein or portion thereof, e.g., apeptide), small molecule (of 2000 amu or less, 1000 amu or less or 500amu or less), protein, virus, bacteria, chemical compound, mixture ofchemical compounds, or an extract made from biological materials such asbacteria, plants, fungi, or animal (particularly mammalian) cells ortissues, or other biologically active agent may be introduced into oneor more of the biological sample holders. In one particularimplementation using an array of biological sample holders, no agent isintroduced into a first row of biological sample holders to preserve acontrol. A first agent is introduced into a second row of biologicalsample holders. Additional agents are added to additional rows of thearray of biological sample holders. The fluorescence of the sensorsintroduced into the biological sample holders may be monitored. Themonitoring preferably begins prior to introduction of the agents andcontinues thereafter. Changes in analyte concentration resulting fromthe introduced agents are then determined. By comparing the changes inanalyte concentration after adding an agent, one can determine theeffect of the agent on the cells being tested.

In certain embodiments, ion-detecting sensors are used to detect ions inwater or other aqueous solutions. In certain embodiments, the supportdeposited with the sensor particles is used to detect the presence ofions in an aqueous solution. In certain exemplary embodiments, thesensors are used to detect ions in water, e.g., tap water or groundwater, to determine the levels of toxic ions in solution or to determinethe hardness of the aqueous solution. In certain exemplary embodiments,the sensors are added to manufacturing solutions to measure ions duringproduction of, e.g., the mass production of soda, ion-restoringbeverages or other ionic drinks. In certain embodiments, the sensors areused in the laboratory to monitor the ion content of a reaction mixtureor stock solution.

Other exemplary embodiments and implementations are disclosed in PCTPublication No. WO2008/063151A2 and U.S. patent application Ser. No.11/888,663, hereby incorporated by reference in their entirety.

The sensors of the invention can be used to monitor the effects ofpharmaceutical agents on biological systems such as the cardiovascularsystem or the circulatory system. Action potentials generated by cardiacor neural cells in culture are defined by a flux of sodium and potassiuminto and out of the cell. In certain embodiments, ion-detecting sensorsof the invention measure this ion flux in cardiac cells accurately andspatially in a high throughput manner.

In certain aspects, the sensors are used in the drug discovery process.In certain such embodiments, the sensors are used to measure theefficacy of a therapy. For example, ion-selective sensors may beemployed to monitor the effect of ion channel-modulating drugs. Inalternative embodiments, sensors are used to screen for cytotoxicsubstances by, for example, determining ionic flux in cardiac cells inresponse to a cytotoxic agent and using these values as a comparison fortesting novel therapeutic agents.

In certain aspects, the invention provides a method for detecting ananalyte in an animal using any of the sensors or sensor particles of theinvention. In certain embodiments, the invention provides a method fordetecting the presence of an analyte in an animal, comprising the stepsof: contacting a sensor particle of the invention with an animal cell ortissue, wherein the sensor particle comprises at least one quantum dotand/or fluorescent dye; a polymer matrix comprising a polymer matrixincluding moieties that couple to an analyte and a chromophoreassociated with the polymer matrix that binds to the moieties in theabsence of the analyte; exposing the particles to light energy thatcauses the quantum dot and/or fluorescent dye to emit photons; using adetector to detect the photons; and determining the presence or absenceof coupled analyte based on the detected photons. In certainembodiments, the particle is implanted within the dermis or epidermis ofan animal. In certain embodiments, the analyte is an ion. In certainembodiments, the analyte is a chelatable analyte. In certainembodiments, the chelatable analyte is glucose.

In certain aspects, the sensors of the invention are implanted intosmall animals to monitor biological responses to new therapeutic agents.In certain embodiments, the implantable sensors are used to study themechanism of disease in small animals. In certain such embodiments, theanimals, such as rats or mice, are, for example, infected with a diseaseand the biological functions are monitored by detecting the signal ofthe implanted optical sensors. In such embodiments, the animal is placedwithin a monitoring element, e.g., a fluorescent monitoring cell similarto a monitoring element used to take X-rays of small animals, whereinthe quantum dots of the sensors are excited, e.g., with UV light, andfluorescence emitted from the sensors within the animal may be detected.

In certain embodiment, the method for detecting an analyte in an animalcomprises implanting the particle below the surface of the epidermis ordermis of the animal. The particle may be implanted intracellularly,while in other embodiments, the sensors are implanted extracellularly.When implanted in tissues, the composition may be taken into a cell orremain external to a cell. The particle may be implanted between about0.05 mm and about 4 mm below the surface of the epidermis or dermis ofthe animal. In certain embodiments, the particle is injected orsurgically inserted within the dermis or epidermis of an animal. Incertain embodiments, the particle is injected within the dermis orepidermis of the animal. In certain embodiments, the particle isinjected in a solution. In certain embodiments, a particle solutioncomprises multiple particles. The particle solution may compriseparticles with an average particle size between 10 nm and 10 microns. Incertain embodiments, the particle solution comprises particles with anaverage particle size between 10 microns and 500 microns such as between50 microns and 200 microns. In certain embodiments, the amount of signaldecrease over time due to fouling and leaching for the implantedparticle sensor is minimal.

In certain embodiments, the implanted particle produces an opticalchange upon contact with a chelatable analyte. In certain embodiments,the optical change is the appearance of a color upon chelation of themoieties of the particle with the chelatable analyte, For example, incertain embodiments, when a colorless particle comes into contact withthe chelatable analyte glucose, the chelatable particle turns red. Incertain embodiments, wherein the particle is implanted in the dermis orepidermis, the color change can be seen from the surface of the skin. Incertain other embodiments, the sensor turns yellow, green, blue, purpleor orange.

In certain embodiments, the particle emits photons when contacted by achelatable analyte which can be detected spectrophotometrically. Theparticle may emit photons immediately upon making contact with theanalyte. In certain embodiments, the particle may emit photons after abrief time such as 1-5 seconds upon making contact with the analyte. Inan exemplary embodiment, when a particle comprising a quantum dotcontacts glucose, the particle emits photons which can be detected witha spectrophotometer. In certain embodiments, the number of photonsdetected can be correlated with the amount of analyte present in amedium, e.g., blood. In certain embodiments, where the particle isimplanted in the dermis or epidermis, the photons can be detectedthrough the skin. In certain embodiments, the detector is a hand heldunit that can be held near the skin to detect photons emitted from thesensor.

The epidermis may vary in thickness depending upon its location and theanimal, but is generally up to about 1 mm thick in a human. Whenimplanted in the epidermis, it is preferred that the particle is placedor implanted of from about 0.05 mm, about 0.06 mm, about 0.07 mm, about0.08 mm, about 0.09 mm, about 0.10 mm, about 0.12 mm, about 0.14 mm,about 0.16 mm, about 0.18 mm, about 0.2 mm, about 0.22 mm, about 0.24mm, about 0.26 mm, about 0.28 mm, about 0.30 mm, about 0.32 mm, about0.34 mm, about 0.36 mm, about 0.38 mm, about 0.40 mm, about 0.42 mm,about 0.44 mm, about 0.46 mm, about 0.48 mm, about 0.50 mm, about 0.52mm, about 0.54 mm, about 0.56 mm, about 0.58 mm, about 0.60 mm, about0.62 mm, about 0.64 mm, about 0.66 mm, about 0.68 mm, about 0.70 mm,about 0.72 mm, about 0.74 mm, about 0.76 mm, about 0.78 mm, about 0.80mm, about 0.82 mm, about 0.84 mm, about 0.86 mm, about 0.88 mm, about0.90 mm, about 0.92 mm, about 0.94 mm, about 0.96 mm, or about 0.98 mmto about 1 mm below the outer surface of the epidermis of an animal. Inanother preferred aspect, the particle is implanted between about 0.1 mmand about 0.15 mm below the surface of the epidermis of the animal.Preferred animals include sheep, goats, cats, dogs, birds, cows, horsesor pigs. A particularly preferred animal is a human.

When implanted in the epidermis of an animal, the particle may existonly days or weeks before the cells containing or surrounding theparticle are shed from the animal. In certain embodiments, the particlewould remain in the position in which it was implanted for 1-4 weeks. Incertain embodiments, the particle will exist up to about 2 weeks beforeremoval through natural replacement of epidermal layers.

In another embodiment, the particle is implanted in the dermis or dermallayers of an animal. The dermis may very in thickness depending upon itslocation and the animal, but is generally from about 1 mm to about 4 mmthick in a human. The dermis is located beneath the epidermis, oftengenerally beginning about 1 mm beneath the epidermis, often generallybeginning about 1 mm beneath the outer surface of the epidermis. Thedermis does not actively shed, so that a particle may existsemi-permanently or permanently in an animal, i.e., remain in the dermisfor months or years. Depending on the thickness of the epidermis anddermis, in certain embodiments, the particle may be implanted or placedin the dermis of from about 1 mm, about 1.1 mm, about 1.2 mm, about 1.3mm, about 1.4 mm, about 1.5 mm, about 1.6 mm, about 1.7 mm, about 1.8mm, about 1.9 mm, about 2.0 mm, about 2.1 mm, about 2.2 mm, about 2.3mm, about 2.4 mm, about 2.5 mm, about 2.6 mm, about 2.7 mm, about 2.8mm, about 2.9 mm, about 3.0 mm, about 3.1 mm, about 3.2 mm, about 3.3mm, about 3.4 mm, about 3.5 mm, about 3.6 mm, about 3.7 mm, about 3.8mm, about 3.9 mm, about 4.0 mm, about 4.1 mm, about 4.2 mm, about 4.3mm, about 4.4 mm, about 4.5 mm, about 4.6 mm, about 4.7 mm, about 4.8mm, or about 4.9 mm to about 5.0 mm beneath the outer surface of theepidermis. In certain preferred embodiments, the particle would beimplanted of from about 1 mm to about 5 mm beneath the surface of theepidermis, with about 2 mm to about 3 mm being particularly preferred.

In certain embodiments, the particle sensor is coupled with an opticalreadout (e.g., placed over the implantation site). In certainembodiments utilizing a glucose-sensitive sensor, a small insulin pumpmay be coupled to the optical readout device. The insulin pump may beconfigured such that the insulin pump is activated to deliver insulin ifthe optical readout detects a level of glucose above a predeterminedvalue.

The invention now being generally described, it will be more readilyunderstood by reference to the following examples which are includedmerely for purposes of illustration of certain aspects and embodimentsof the present invention, and are not intended to limit the invention inany way.

EXAMPLES

Nano-scale polymer-coated quantum dots: Commercially available quantumdots (Evident Technologies, Troy, N.Y.) were dispersed in a polymericmatrix. In order to make the dispersion homogeneous, a ligand exchangewas performed to add a decane-thiol to the surface of the quantum dot.The alkylated surface proved more miscible with the lipophilic polymermatrix. After a homogeneous distribution was obtained, nanoscale sensorswere produced by sonicating the polymeric matrix dissolved in THF,containing all of the sensing elements including quantum dots, in anaqueous solution of PEG-lipid surface modifier. The resulting nanosensorsolution was filtered to remove larger pieces of polymer. The resultingsensor suspension fluoresced brightly when viewed in a wide-fieldfluorescence microscope (FIG. 18).

Inner-filter effect: Nanometer-sized glucose-sensitive quantum dots(GSQDs) in solution are shown in FIG. 19. The absorbance changes frompurple to yellow are easily seen by eye in FIG. 19 (left). The samesamples of nanosensors under UV excitation are shown in FIG. 19 (right).The sample that was visually purple does not absorb the 525 nm emissionof the quantum dots and fluoresces brightly. The yellow GSQD absorbs thefluorescence emission of the quantum dot and has minimal emission.

Response to glucose: A polymer matrix containing the sensing componentsalizarin, pyrene boronic acid and additive, was immobilized to thebottom of a micro-well for calibration. Response to glucose and fructosewas measured, the average±SEM is shown in FIGS. 20, n=6 and 8 forcontrol and monosaccharides, respectively.

Biocompatibility: In vitro biocompatibility studies produced noindications of cellular injury thus far. For instance, LIVE-DEAD assaysshowed no differences from controls in the amount of cell death. Inaddition, the degree of cytotoxicity was determined by incubating thenanosensors overnight with HEK 293 cells and measuring the degree ofcellular injury with an MTT assay. These results were compared to othernanoparticles and are shown in FIG. 10. The ion-sensitive quantum dot(ISQD) nanosensors show no cellular toxicity compared to controls overthe course of 72 hours after incubation. This result is also seen for100 nm diameter gold nanoparticles.

Initiated chemical vapor deposition (iCVD): iCVD films of pHEMA may bedeposited in a process disclosed in Gleason et al., PCT WO 2007/145657A2, hereby incorporated by reference in its entirety.

Photoinitiated chemical vapor deposition (piCVD): piCVD films of pHEMAwere deposited on surfaces in a reactor similar to the reactor disclosedin Gleason et al, PCT WO 2007/145657 A2 for iCVD deposition. A low-powerultraviolet lamp (Model UVG-54, UVP) emitting ultraviolet light at 254nm wavelength was mounted 9.0 cm above the reactor, with a 2.5 cm thickquartz viewport allowing the light to enter the reactor. The substratestage was located 3.3 cm into the reactor. Thus, the total distance fromthe substrate to light source was 14.8 cm. The light intensity at thisdistance was 50 μW/cm². A laser interferometer allowed for real timetracking of the deposited film thickness and termination of growth atthe desired film thickness. FIG. 21 depicts an exemplary piCVD reactorsystem.

HEMA monomer (99+%, Aldrich) was used as-received without any additionalpurification. The liquid monomer was vaporized in a stainless-steel jarand its vapor was metered into the reactor at 2 sccm, i.e., 2 standardcubic centimeters per minute, through a mass-flow controller (Model1152, MKS). No separate photoinitiator was used. The chamber pressurewas maintained by a throttling butterfly valve (Model 653V, MKS) and thesubstrate temperature (T_(s)) was controlled via backside contact of thedeposition stage with temperature-controlled water lines. Twoexperimental series were conducted for this study: one investigating theeffect of mean free path of the vapor (experimental series A) and theother investigating the effect of substrate temperature (experimentalseries B). The experimental conditions are summarized in the tablebelow. All films were deposited on flat silicon wafers.

Experimental Pressure Flowrate Condition T_(s) (° C.) (mtorr) HEMA(sccm) P_(M)/P_(M) ^(sat) A1 30 100 2.5 0.42 A2 30 100 2.0 0.42 A3 30100 1.5 0.42 A4 30 100 1.0 0.42 B1 20 100 2.0 0.94 B2 25 100 2.0 0.63 B330 100 2.0 0.42 B4 40 100 2.0 0.20 Note: P_(M)/P_(M) ^(sat) is thepartial pressure of the monomer divided by its saturation pressureevaluated at the stage temperature.

Additionally, experimental condition B2 was also used to deposit filmson large silica microspheres of diameter 50-100 μm (Polysciences) andsmall, monodisperse spheres of nominal diameter 5.0 μm (Bangslab). Thelarge microspheres were placed in a petri dish in the vacuum chamber,manually agitated after every 100 nm of deposition to prevent particleagglomeration. The small particles were diluted in tetrahydrofuran,dispersed onto a silicon wafer, dried overnight, and then placed in thereactor for deposition. This experimental condition was also used todeposit 100 nm of film onto a flat optode sensor, whose preparation hasbeen described elsewhere. The as prepared optode was coated withoutfurther modification. The responses of the coated and uncoated optodeswere characterized via fluorometry.

Swelling characterization. The film swelling capacity was determined viaspectroscopic ellipsometeric (M-2000, J. A. Woollam) measurements ofthickness. The wafer was cut into 2.5 cm×8 cm strips prior to measuringthickness. Dry film thicknesses were determined by spectroscopicellipsometry at an incident angle of 75°. The data were fit to aCauchy-Urbach isotropic model (WVASE 32, J. A. Woollam). The films werethen mounted in a liquid cell (J. A. Woollam) and the cell was injectedwith pH 7.4 phosphate buffer solution (cellgro, Mediatech).Ellipsometric data were then collected 1, 3, 5, 10, and 30 minutesfollowing injection of the buffer solution. In all cases, the filmreached its equilibrium film thickness (within 1 nm) after 5 minutes.The water content of the swollen film was determined by dividing theincrease in film thickness by the total thickness of the swollen film.This method of determining equilibrium swollen water content has beenpreviously shown to closely match the more complex effective mediumapproximation. To test the stability of the polymer films andreversibility of the swelling response, the films were rinsed indeionized water, dried in a vacuum oven for 30 minutes, and the dry andswollen thicknesses were obtained again.

Interaction with proteins. X-ray photoelectron spectroscopy (XPS) wasused to quantify the degree of non-specific protein adhesion on thep(HEMA) films. A 1 wt % protein solution was prepared by dissolving 200mg of bovine serum albumin (Fraction V, Sigma Aldrich) in 19.8 mLphosphate buffer solution. Three pieces of sample B2 and three pieces ofa bare silicon wafer were incubated in the protein solution for threehours at 37° C. Samples were then rinsed with approximately 5 mL buffersolution to remove any non-bound protein and dried gently undernitrogen. The surface nitrogen content of each sample was thenquantified by XPS (Kratos AXIS Ultra) survey scans.

Particle characterization. After coating with pHEMA, the largemicrospheres were freeze-fractured and the particle cross-section wasimaged via scanning electron microscopy (SEM, JEOL-5910). For the smallmicrospheres, both uncoated and coated particles were imaged(JEOL-6320FV) and their diameters measured via built-in image processingin the SEM software (JEOL Orion).

Chemical structure. FIG. 22 compares a typical FTIR spectrum of piCVDpHEMA to a polymer standard. The absence of peaks in due to unsaturatedcarbon at 1640-1660 cm⁻¹ or 3000-3100 cm⁻¹ indicates that monomerpolymerized through its vinyl moiety to form polymer. Both the piCVD andstandard polymer exhibit a broad peak at 3200-3600 cm⁻¹, correspondingto the hydroxyl group, and a sharp peak at 1725-1730 cm⁻¹, correspondingto carbonyl stretching. The spectra therefore demonstrate that the piCVDof HEMA monomer proceeds through a free-radical mechanism whileretaining the side-group functionality. Because HEMA is the only speciesintroduced into the reactor during synthesis, the polymerization islikely initiated by the excitation of HEMA monomer. Indeed, at UVwavelengths below 267 nm, carbonyl species are known to decompose intoradical species, which in turn can initiate a free-radicalpolymerization. Despite this, the similarity between the piCVD film andthe polymer standard indicates that the vast majority of the pendanthydroxyl and carbonyl groups are retained.

Film structure and swelling properties. To function as a protectiveoverlayer for biosensor, a thin film preferably allows for the passageof small analytes from the medium to the sensor. It is thereforepreferable that the film swell when in contact with a biological mediumwhile remaining adhered to the sensor substrate. All the filmssynthesized in this study exhibited a rapid, reversible swellingresponse while maintaining adhesion to the substrate. As characterizedby in situ spectroscopic ellipsometry, the films reached theirequilibrium swollen water content within 5 min of submersion in pH 7.4buffer solution. Upon rinsing in deionized water and drying undervacuum, the films returned to their original thickness. When submergedagain, the films rapidly returned to their swollen state. FIG. 23 showsa typical response to several of these swell/dry cycles. The recovery ofthe original thickness after each swell/dry cycle indicates that polymerdoes not leach out of the film when submerged in buffer solution, animportant property for any material with potential for biological orphysiological use. It also indicates that the crosslinking within thefilm is not due exclusively to physical entanglements; purely physicalcrosslinking would result in the loss of film in the swelling andwashing steps.

In order to control the swellability of these films, it is preferable tounderstand whether the polymerization is initiated in the vapor phase oron the substrate surface. FIG. 24 a (top) shows the swellability as afunction of vapor residence time in the reactor (experimental series A).The residence time was determined by dividing the chamber volume (5467mL) by the vapor flowrate. Changing the residence time alters UVexposure time for gaseous monomer molecules as they pass through thereactor. The relative independence of film swellability on irradiationtime suggests that the polymerization is not a vapor phase process (FIG.24 a). These results suggest that irradiation chemistry at the surfaceis the dominant initiation mechanism for film deposition. To test thishypothesis, the surface concentration of monomer was systematicallyvaried while holding residence time fixed (experimental series B). Thiswas accomplished by varying the ratio of the partial pressure of themonomer to its saturation pressure at the stage temperature, P_(M)/P_(M)^(sat). This ratio will be referred to as the fractional saturation ofthe monomer and has previously been shown to control the concentrationof monomer at the substrate. The saturation pressure is evaluated usingthe Clapeyron equation. FIG. 24 b displays a strong dependence ofswellability on P_(M)/P_(M) ^(sat), consistent with a polymerizationmechanism which is primarily a surface process. Changing P_(M)/P_(M)^(sat), and therefore the surface concentration of monomer duringsynthesis, allows for the control of the swelling properties.

The moderate degree of swelling and the reversibility of the swellingresponse suggest that the films are highly crosslinked. The origin ofthe crosslinking is unclear since no separate crosslinker was introducedinto the reactor. However, if the pendant carbonyl group can bedecomposed into radicals under UV irradiation as suggested earlier, theneach pendant group on the polymer chain can potentially act as acrosslinker. Furthermore, HEMA monomer may undergo transesterificationor etherification to produce dimethacrylates, which are commonly used ascrosslinking agents. Finally, physical crosslinking via chainentanglement is also a possibility, although purely physicalcrosslinking is unlikely given the stability of the film over severalswell/dry cycles. Understanding the degree of crosslinking, regardlessof the nature of the crosslinks themselves, is preferable forunderstanding how these films can potentially be used as a protectiveoverlayer for sensors in a biological environment. Non-specific proteinadhesion can potentially damage the device, so the film preferably maybe crosslinked enough prevent transport of proteins from the medium tothe device surface. At the same time, the analyte preferably may be ableto permeate the film.

The crosslinking is intimately related to the swollen water content ofthe film; for highly crosslinked networks, the swollen water content andthe average molecular weight between crosslinks satisfy the followingequation:

$\begin{matrix}{\frac{1}{{\overset{\_}{M}}_{C}} = {\frac{2}{{\overset{\_}{M}}_{n}} - \frac{{{\frac{\overset{\_}{v}}{V_{1}}\left\lbrack {{\ln\left( {1 - v_{2,s}} \right)} + v_{2,s} + {\chi\left( v_{2,s} \right)}^{2}} \right\rbrack}\left\lbrack {1 - {\frac{M_{r}}{2{\overset{\_}{M}}_{C}}\left( v_{2,s} \right)^{2/3}}} \right\rbrack}^{3}}{\left( {\left( v_{2,s} \right)^{1/3} - {\frac{1}{2}v_{2,s}}} \right)\left( {1 + {\frac{M_{r}}{2{\overset{\_}{M}}_{C}}\left( v_{2,s} \right)^{1/3}}} \right)^{2}}}} & (1)\end{matrix}$where M _(C) is the average molecular weight between crosslinks, ν isthe specific volume of pHEMA, χ is the Flory-Huggins interactionparameter, V₁ is the molar volume of water, M_(r) is the molecularweight of the HEMA repeat unit, and v_(2,s) is the ratio of thethickness of the dry polymer to the thickness of the swollen polymer.This theory is developed for linear polymer chains of number-averagemolecular weight M _(n) that undergo crosslinking by the introduction ofa crosslinking agent. Measuring M _(n) for the piCVD films is difficultbecause the crosslinking occurs in situ and without a separate chemicalspecies. Commonly, M _(n) is assumed to be large enough that the term inwhich it appears can be neglected. This assumption provides an upperbound on M _(c). The molecular weight between crosslinks can in turn beused to compute the average mesh size in the swollen film. It should benoted that the crosslink density as calculated by (1) is an effectivevalue that does not distinguish between physical entanglements andchemical crosslinking. FIG. 25 shows the average mesh size for filmsB1-B4 as computed by (1). Each of these mesh sizes is large enough toallow for the passage of small molecule analytes such as metal cations(e.g., sodium or potassium) or sugars (e.g., glucose). However, thesemesh sizes are too small to allow for the permeation of largebiomolecules such as proteins. For example, albumin is a 3.8 nm×15.0 nmellipsoid molecule and fibrinogen is a 9 nm×45 nm ellipsoid.

Protein adhesion. While the films are capable of protecting devicesurfaces from contact with proteins, the films themselves should alsoresist protein adhesion. XPS characterization of the piCVD filmsfollowing incubation in a protein solution (BSA) provided a convenientproxy for measuring the degree of protein adhesion. As the p(HEMA) filmdoes not contain any nitrogen, any nitrogen detected by the highlysurface-sensitive XPS must be due to surface-bound proteins. FIG. 26compares the nitrogen content of a p(HEMA) surface incubated in asolution of bovine serum albumin (BSA) with a control silicon surface.The p(HEMA) film exhibits an eight-fold decrease in surface nitrogensignal over bare silicon, corresponding to a reduction of surface boundproteins.

Sensor and particle coating. To demonstrate the gentle nature of thepiCVD process, a sodium-sensing optode was coated with 100 nm of pHEMA.The optode is a chromoionophore and ionophore in a polymer matrix castas a film (<10 μm thickness) on a 1 cm diameter glass coverslip. Theresponses of both an uncoated optode and a coated optode to varyinglevels of sodium ion concentration are shown in FIGS. 27 a and 27 b,respectively. It is evident that the piCVD process does not damage theoptode functionality.

The coated optode also shows little or no degradation in response timewhen compared to the uncoated optode. The response of the device isgoverned by the diffusion of sodium ion through optode matrix, which isseveral microns thick. The nanoscale thickness of the overlaying pHEMAfilm does not add significantly to the distance that the ion mustdiffuse. Additionally, the fact that the sodium ion diffuses through thefilm is consistent with the calculated mesh size. Small moleculeanalytes, such as ions, have no difficulty diffusing through a film witha mesh size on the order of several nanometers.

Because piCVD is a dry process, the geometries that can be coated withpHEMA are not limited to planar surfaces. Indeed, many sensors ofphysiologically relevant analytes are being miniaturized asmicoparticles to take advantage of high surface areas and reductions inresponse time. As a dry process, piCVD can conformally coatmicrogeometries while avoiding the effects of solvent tension, whichtends to result in particle agglomeration. FIG. 28 shows a cross sectionof a ˜50 μm microsphere coated with approximately 1 μm of pHEMA. Thecoating is continuous and conformal around the outside of the particle.FIG. 29 compares SEM images of uncoated and coated monodispersemicroparticles. The uncoated microspheres have an average diameter of5.06±0.04 μm and the coated microspheres have an average diameter of5.39±0.04 μm, indicating that the particles were coated withapproximately 165 nm of hydrogel.

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments of the invention described herein. Such equivalents areintended to be encompassed by the following claims.

Incorporation by Reference

All publications and patents mentioned herein are hereby incorporated byreference in their entirety as if each individual publication or patentwas specifically and individually indicated to be incorporated byreference. In case of conflict, the present application, including anydefinitions herein, will control.

The invention claimed is:
 1. A sensor for detecting an analyte selectedfrom: an ionic analyte, wherein the sensor comprises a polymer matrixcomprising a fluorescence source, an ionophore and a chromoionophore,wherein in an initial state photons emitted from the fluorescence sourceare absorbed by the chromoionophore, and when the ionophore associateswith the ionic analyte, the chromoionophore stops absorbing photonsemitted by the fluorescence source; an ionic analyte, wherein the sensorcomprises a polymer matrix comprising a fluorescence source, anionophore and a chromoionophore, wherein in an initial state photonsemitted from the fluorescence source are not absorbed by thechromoionophore, and when the ionophore associates with the ionicanalyte, the chromoionophore absorbs photons emitted by the fluorescencesource; and a chelatable analyte, wherein the sensor comprises a polymermatrix, comprising a polymer including moieties that bind the chelatableanalyte, optionally a fluorescence source, and a chromophore associatedwith the polymer matrix that binds to the moieties in the absence of thechelatable analyte; wherein the sensor comprises a continuous coating,penetrable by the analyte, at least partially covalently bound to thesurface of the polymer matrix.
 2. The sensor of claim 1, wherein thesensor detects an ionic analyte selected from K³⁰, Na⁺, Ba²⁺, Li³⁰ , NH₄⁺, Ca²⁺, Cl⁻and NO₃ ⁻.
 3. The sensor of claim 1, wherein the sensordetects a chelatable analyte wherein the chelatable analyte is glucose.4. The sensor of claim 3, wherein the moieties that bind the chelatableanalyte comprise boronic acids and/or boronic esters.
 5. The sensor ofclaim 1, wherein the fluorescence source is selected from one or morefluorescent dyes and quantum dots.
 6. The sensor of claim 1, wherein thecoating comprises one or more hydroxyethylmethacrylate monomers.
 7. Thesensor of claim 6, wherein the thickness of the sensor coating rangesfrom 1 nm to 100 microns.
 8. The sensor of claim 1, wherein the sensoris a nanoparticle.
 9. The sensor of claim 8, wherein the diameter of thenanoparticle excluding the coating is between 5 nm and 300 nm.
 10. Amethod for detecting the presence of a chelatable analyte in a medium,comprising: contacting a sensor of claim 1 with the medium; exposing thefluorescence source to light energy that causes the fluorescence sourceto emit photons; using a detector to detect the photons; and determiningthe presence or absence of bound chelatable analyte based on thedetected photons.
 11. The method of claim 10, wherein contacting thesensor with the medium comprises implanting the sensor into a dermis orepidermis of an animal.
 12. The sensor of claim 1, wherein the sensor isimplanted within a dermis or epidermis of an animal.
 13. A method fordetecting a characteristic of a living cell, the method comprising:contacting the cell with at least one sensor, wherein the sensor bodycomprises a polymer, a fluorescence source that fluoresces at a firstwavelength, a chromoionophore that absorbs photons of the firstwavelength in one state and does not absorb photons of the firstwavelength in a second state, wherein the states are indicative of thecharacteristic of the cell, and a conformal continuous coating,penetrable by the analyte, at least partially covalently bound to thesensor body, and exciting the fluorescence source with a light sourcecausing the fluorescence source to fluoresce, and detecting a signalfrom the sensor.
 14. The method of claim 13, wherein the characteristicis the presence of an ionic analyte.
 15. The method of claim 14, whereinthe sensor further comprises an ionophore that selectively binds theionic analyte.
 16. The method of claim 13, further comprisingstimulating the cell so as to affect the characteristic.
 17. The methodof claim 14, wherein the fluorescence has an intensity indicative of theconcentration of ionic analyte.
 18. The method of claim 14, wherein theionic analyte is K⁺, Na⁺, Ba² ⁺, Li⁺, NH₄ ⁺, Ca²⁺, Cl⁻and NO₃ ⁻.
 19. Themethod of claim 13, wherein contacting the cell with at least one sensorcomprises implanting the least one sensor into a dermis or epidermis ofan animal.